Joint structure

Abstract

To provide a joint structure that can suppress a formation of a step on an outer surface of the joint section.SOLUTION: The joint structure consists of two reinforcement materials adhered to a surface of a structure. Each reinforcement material is formed into a sheet by arranging multiple spaced-apart wires with a cross-sectional area of less than 75 mm2, and they overlap each other so that the wires of one reinforcement material are positioned between the wires of the other.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a joint structure. [Background technology]

[0002] In the civil engineering and construction fields, when structures need repair or reinforcement due to deterioration over time or changes in use, reinforcing materials such as FRP sheets with wires arranged in a blind pattern are bonded with time-hardening materials. In this case, when the length of the area to be reinforced is longer than the dimensions of the reinforcing material, a joint structure has been used in which the reinforcing materials are overlapped by a specified length in the thickness direction of the reinforcing material.

[0003] However, in the above-described joint structure, a step occurs on the outer surface of the joint due to the overlapping of the reinforcing materials, and therefore unevenness must be corrected at the joint (the part where the reinforcing materials are overlapped) using a time-hardening material. In addition, since the overlapping reinforcing materials are spaced apart from the structure, the amount of time-hardening material required for adhesion increases, which may result in an increase in the weight of the structure.

[0004] Furthermore, such differences in level can cause construction defects, such as the ends lifting, when reinforcement material is installed on top of them because the reinforcement material does not conform to the differences in level, which can make construction more complicated by having to correct the unevenness again or change the joint position.

[0005] In response to this, Patent Documents 1 and 2 disclose a structure in which two reinforcing materials are butted together inside a joint member without being overlapped. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-25100 A [Patent Document 2] Patent No. 3276800 Summary of the Invention [Problem to be solved by the invention]

[0007] In the structures of Patent Documents 1 and 2, in order to obtain the required strength, the joint member needs to have a certain thickness, and the problem of steps occurring on the outer surface due to the joint member is not solved.

[0008] An object of the present invention is to provide a joint structure that can suppress the occurrence of steps on the outer surface of the joint portion. [Means for solving the problem]

[0009] The joint structure of the first embodiment has a cross-sectional area of ​​75 mm 2 Two sheets of reinforcing material are formed into a sheet-like shape by arranging multiple wires of less than 1 mm at intervals, and are overlapped so that the wires of one reinforcing material are arranged between the wires of the other reinforcing material and adhered to the surface of the structure.

[0010] In the joint structure of the first embodiment, two plate-shaped reinforcing materials are stacked so that the wire material of one reinforcing material is arranged between the wire material of the other reinforcing material.Therefore, compared to when two plate-shaped reinforcing materials are stacked so that the wire material of one reinforcing material overlaps with the wire material of the other reinforcing material in the thickness direction, the thickness of the joint portion (the portion where the reinforcing materials are stacked) is reduced, and the occurrence of steps on the outer surface of the joint portion can be suppressed.

[0011] In the joint structure of the second embodiment, in the joint portion where the two reinforcing materials are stacked in the first embodiment, the distance along the thickness direction between the cross-sectional center of the wire in one reinforcing material and the cross-sectional center of the wire in the other reinforcing material is shorter than the thickness of the reinforcing materials.

[0012] In the joint structure of the second embodiment, the distance along the thickness direction between the center of the wire in one reinforcing material and the center of the wire in the other reinforcing material is shorter than the thickness of the reinforcing material, so that the thickness of the joint portion is reduced compared to when that distance is equal to or greater than the thickness of the reinforcing material, and the occurrence of steps on the outer surface of the joint portion can be suppressed.

[0013] In the joint structure of the third aspect, in the first or second aspect, the interval between the wires in the reinforcing material is larger than the diameter of the wires.

[0014] In the joint structure of the third embodiment, the spacing between the wires in the reinforcing material is larger than the diameter of the wires. Therefore, it is possible to place the entire wire of one reinforcing material between the wires of the other reinforcing material, thereby reducing the thickness of the joint portion and suppressing the occurrence of steps on the outer surface of the joint portion.

[0015] In the joint structure of the fourth aspect, in any one of the first to third aspects, the reinforcing material is a fiber-reinforced sheet in which a plurality of fiber-reinforced plastic strands containing reinforcing fibers are aligned in a curtain-like shape in the longitudinal direction and the fiber-reinforced plastic strands are fixed to each other with a wire fixing material having a thickness thinner than the diameter of the wires.

[0016] In the joint structure of the fourth embodiment, the thickness of the wire fixing material that fixes the fiber-reinforced plastic wires to each other is thinner than the diameter of the wires. Therefore, compared to when the thickness of the wire fixing material is the same as the diameter of the wires, the thickness of the joint portion is reduced, and the occurrence of steps on the outer surface of the joint portion can be suppressed. Effect of the Invention

[0017] According to the joint structure of the present invention, the occurrence of steps on the outer surface of the joint portion can be suppressed. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic front cross-sectional view showing a state in which a fiber-reinforced sheet is bonded to a surface of a structure with a bonding material by a reinforcement method using the joint structure according to this embodiment. FIG. [Diagram 2] 1 is a schematic cross-sectional side view showing a state in which a fiber-reinforced sheet is bonded to the surface of a structure with a bonding material by a reinforcement method using the joint structure according to the present embodiment. [Diagram 3]1 is a schematic cross-sectional view for explaining a base treatment step in a reinforcement method in which the joint structure according to the present embodiment is used. FIG. [Figure 4] 1 is a schematic cross-sectional view for explaining a primer application step in a reinforcement method in which the joint structure according to the present embodiment is used. FIG. [Diagram 5] 1 is a schematic cross-sectional view for explaining a binder application step in a reinforcement method in which the joint structure according to the present embodiment is used. FIG. [Figure 6] FIG. 2A shows a fiber-reinforced sheet according to the present embodiment, and FIG. 2B shows a fiber-reinforced plastic strand of the fiber-reinforced sheet according to the present embodiment. [Figure 7] FIG. 2 is a perspective view showing a joint structure according to the present embodiment. [Figure 8] FIG. 2 is a plan view showing the joint structure according to the present embodiment. [Figure 9] 8 is a cross-sectional view taken along line AA in FIG. 7, showing a joint portion in the joint structure according to the present embodiment. [Figure 10] FIG. 2 is a cross-sectional view showing a cross section of a fiber-reinforced sheet according to the present embodiment. [Figure 11] FIG. 4 is a perspective view showing another example of the fiber-reinforced sheet according to the present embodiment. [Figure 12] FIG. 11 is a perspective view showing a joint structure according to a comparative example. [Figure 13] FIG. 4 is a side view showing a joint structure according to a comparative example. [Figure 14] FIG. 2 is a diagram showing a procedure for producing a test piece in Example 1. [Figure 15] FIG. 2 is a diagram showing a procedure for producing a test piece in Comparative Example 1. [Figure 16] FIG. 1 is a diagram showing a procedure for producing a test specimen of Example 2. [Figure 17] FIG. 13 is a diagram showing a procedure for producing a test specimen of Comparative Example 2. [Figure 18] Table 1 shows the evaluation results. [Figure 19] Table 2 shows the evaluation results. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

[0020] In this specification, a numerical range indicated using "to" means a range including the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In addition, in a numerical range described in a stepped manner in this specification, an upper limit or lower limit value described in a certain numerical range may be replaced with an upper limit or lower limit value of another stepped numerical range. In addition, in a numerical range described in this specification, an upper limit or lower limit value described in a certain numerical range may be replaced with a value shown in an example. In this specification, the amount of each component means the total amount of multiple substances when there are multiple substances corresponding to each component, unless otherwise specified.

[0021] <Reinforcement method> 1 and 2, a joint structure 94 as an example of the joint structure of the present invention is used in a method for reinforcing a structure 90 in which a fiber-reinforced sheet 40 is bonded to a surface 90A of the structure 90 with a binder. In reinforcing the structure 90, since the area to be reinforced is often longer than the dimensions of the fiber-reinforced sheet 40, a joint structure 94 in which fiber-reinforced sheets 40 are overlapped at a predetermined length is used. In this reinforcement method, as an example, the structure 90 is reinforced while the joint structure 94 is created using a primer 20, a binder 50, and a fiber-reinforced sheet 40.

[0022] In the following, first, a structure 90, a primer 20, a binder 50, and a fiber-reinforced sheet 40, which are targets of the reinforcement method, will be described. Then, a joint structure 94, each step of the reinforcement method including a joint preparation step for preparing the joint structure 94, the effects of this embodiment, and an evaluation of this embodiment will be described.

[0023] <Structure 90> The structure 90 to be reinforced by the reinforcement method using the joint structure 94 is, for example, a concrete structure. The concrete structure is, for example, a bridge deck. The concrete structure may be a reinforced concrete structure having reinforcing bars therein, or an unreinforced concrete structure having no reinforcing bars therein.

[0024] In addition, concrete structures are not limited to bridge decks, but may include, for example, structures other than bridge decks (e.g., bridge girders and piers), tunnels, buildings, etc., as long as they are structures made of concrete.

[0025] Furthermore, the structure 90 is not limited to a concrete structure, but may be, for example, a structure made of mortar, ceramics, metal, glass, or the like, as long as it is a structure to be reinforced.

[0026] Hereinafter, the surface 90A of the structure 90 reinforced by the reinforcing method according to the present embodiment may be referred to as the reinforced surface 90A. The reinforced surface 90A is, for example, a bottom surface facing downward (specifically, downward in the direction of gravity) of the structure 90. The reinforced surface 90A may be a side surface of the structure 90 (specifically, a surface along the direction of gravity or a surface inclined with respect to the direction of gravity), and in this embodiment, the reinforced surface 90A is, for example, a surface on which dripping of the bonding material 50 may occur (i.e., a surface excluding a horizontal surface facing upward in the direction of gravity).

[0027] <Primer 20> The primer 20 is used to strengthen the adhesive strength between the surface 90A of the structure 90 to be reinforced and the binder 50. There are various types of primer 20, including solvent-free, solvent-based, and water-based primers, and there are epoxy resin-based primers, acrylic resin-based primers, etc., but in the present invention, the primer 20 is not particularly limited, and it is not necessarily required to use it.

[0028] <Binding material 50> The binder 50 not only bonds the reinforcing material 50 to the structure 90, but also bonds the reinforcing materials 50 together in the joint structure 94. Inorganic binders such as cement mortar and polymer cement mortar, and resin binders such as epoxy resins are commonly used in methods of reinforcing structures with fiber-reinforced sheets 40; however, in the present invention, the material of the binder 50 is not particularly limited as long as the joint strength and the function of the binder 50 to bond the reinforcing material 50 to the structure 90 are exhibited.

[0029] <Fiber reinforced sheet 40> The fiber-reinforced sheet 40 is an example of a reinforcing material, and is a sheet material that is bonded to a surface 90A to be reinforced of a structure 90 by a bonding material 50 to reinforce the structure 90, as shown in FIGS.

[0030] As shown in Fig. 6(A) and Fig. 7 to Fig. 9, this fiber reinforced sheet 40 is formed into a sheet shape by arranging a plurality of fiber reinforced plastic strands 43 at intervals. Note that the sheet shape refers to a shape in which the dimension T40 in the thickness direction (Y direction in Fig. 9) is smaller than the dimension in the width direction (X direction in Fig. 9). The sheet shape can also be called, for example, a plate shape or a film shape.

[0031] Specifically, the fiber reinforced sheet 40 is a fiber reinforced sheet 40 in which a plurality of fiber reinforced plastic strands 43 including reinforcing fibers 42 are aligned in a curtain shape in the longitudinal direction and fixed to each other by a strand fixing material 45. In this embodiment, the fiber reinforced sheet 40 is disposed inside a binder layer made of a binder 50.

[0032] As the reinforcing fiber 42, for example, organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester, etc., basalt fiber, carbon fiber, glass fiber, metal fiber such as steel fiber, etc., can be used alone or in combination of two or more kinds. However, examples of reinforcing fibers are not limited to these.

[0033] Specifically, as shown in Fig. 6(A)(B), a fiber sheet (so-called strand sheet) can be used as the fiber-reinforced sheet 40, in which a plurality of fiber-reinforced plastic strands 43 including reinforcing fibers 42 are aligned in a curtain-like shape in the longitudinal direction and the strands 43 are fixed to each other with a strand fixing material 45. As shown in Fig. 6(B), the fiber-reinforced plastic strands 43 are formed by impregnating the reinforcing fibers 42 with a matrix resin 47 and curing the matrix resin 47. For the matrix resin 47, a thermosetting resin such as a room-temperature curing or thermosetting epoxy resin, vinyl ester resin, acrylic resin, unsaturated polyester resin, or phenol resin, or a thermoplastic resin such as an in-situ polymerization type phenoxy resin, nylon, or vinylon can be used. Preferably, an epoxy resin, which is a thermosetting resin, is used.

[0034] Fiber-reinforced plastic wire 43 has a cross-sectional area of ​​75 mm 2 The diameter is set to be less than 9.77 mm, for example.

[0035] In the fiber reinforced sheet 40, the spacing S2 (see FIG. 10) between the fiber reinforced plastic strands 43 is set to 10 mm or less. If the spacing S2 between the fiber reinforced plastic strands 43 exceeds 10 mm, the number of fiber reinforced plastic strands 43 per unit area of ​​the fiber reinforced sheet 40 decreases, and the reinforcing effect decreases.

[0036] In addition, in the joint structure 94, from the viewpoint that the fiber reinforced plastic strands 43 of one fiber reinforced sheet 40 are disposed between the fiber reinforced plastic strands 43 of the other fiber reinforced sheet 40 as described later, it is desirable that the spacing S2 between the fiber reinforced plastic strands 43 be larger than the diameter D2 (see FIG. 10) of the fiber reinforced sheet 40. More desirably, the spacing S2 between the plastic strands 43 is larger than the diameter D2+1 mm of the plastic strands 43, and most desirably is equal to or larger than the diameter D2+1.5 mm of the plastic strands 43.

[0037] <Joint structure of fiber reinforced sheet 40> 7 to 9, in a joint structure 94 according to this embodiment, two fiber reinforced sheets 40 are overlapped such that the fiber reinforced plastic strands 43 of one fiber reinforced sheet 40 are disposed between the fiber reinforced plastic strands 43 of the other fiber reinforced sheet 40, and are bonded to a reinforced surface 90A (see FIGS. 1 and 2) of a structure 90. In the joint structure 94, stress is transmitted via a bonding material 50.

[0038] In the joint structure 94, two fiber reinforced sheets 40 are overlapped to form a joint portion 96. The joint portion 96 is a portion of the joint structure 94 where the fiber reinforced sheets 40 are overlapped.

[0039] Furthermore, as shown in FIG. 9 , in a joint portion 96 where two fiber reinforced sheets 40 are stacked, the distance L1 along the thickness direction between the cross-sectional center 43A of the fiber reinforced plastic wire 43 in one fiber reinforced sheet 40 and the cross-sectional center 43B of the wire in the other fiber reinforced sheet 40 is shorter than the thickness T40 of the fiber reinforced sheet 40.

[0040] In the joint structure 94, the two fiber reinforced sheets 40 are overlapped such that the joint portion 96 has a length of 100 mm or more and 400 mm or less, and the distance L1 along the thickness direction is 3 / 4 or less of the diameter of the fiber reinforced plastic strand 43 of the fiber reinforced sheet 40. The length of the joint portion 96 is preferably 100 mm or more and 300 mm or less, and the distance L1 is preferably 1 / 2 or less of the diameter of the fiber reinforced plastic strand 43.

[0041] In the joint structure 94, the structure in which two fiber reinforced sheets 40 are overlapped is not limited to a structure in which only two fiber reinforced sheets 40 are overlapped, and may be a structure in which three or more fiber reinforced sheets 40 are overlapped. Also, a structure in which two fiber reinforced sheets 40 are installed so that the distance L1 is 0, and then two more fiber reinforced sheets 40 are installed in the same manner so that the distance L1 is also 0, and this is repeated multiple times may be used.

[0042] <Modifications of the fiber-reinforced sheet 40> In the above embodiment, the fiber reinforced sheet 40 shown in Figs. 6(A) and (B) is used as an example of the reinforcing material, but the present invention is not limited to this.

[0043] The fiber-reinforced sheet 40 may be a fiber-reinforced sheet 40 having a powder attached to the outer periphery of a plurality of fiber-reinforced plastic strands 43, as described below.

[0044] The powder is not particularly limited in material, and may be either an inorganic material such as silica sand or an organic material such as synthetic resin, and the average particle size is, for example, 0.900 mm or less, and is attached to the fiber-reinforced sheet 40 at, for example, 0.2 to 2 kg / m2 per unit area. The powder is attached by using an adhesive or binder, or by softening the matrix resin of the fiber-reinforced plastic wire 43 by heating or the like, and fusing or welding. If the average particle size of the powder exceeds 0.900 mm, the powder will be caught by a rubber spatula when the fiber-reinforced sheet 40 is pressed and embedded, resulting in reduced workability. If the amount of attachment to the unit area of ​​the fiber-reinforced sheet 40 is less than 0.2 kg / m2, the adhesiveness will be reduced when an inorganic material such as polymer cement mortar is used as the binder 50. There is no particular limit to the lower limit of the average particle size of the powder, but if it is too small, the safety, workability, and material cost of the attachment work to the fiber-reinforced sheet will be deteriorated, so the average particle size is preferably set to 0.07 mm or more. The amount of powder attached to the fiber reinforced sheet 40 is preferably 0.4 kg / m2 or more.

[0045] If the average particle size of the powder exceeds 0.900 mm, or if the amount of adhesion per unit area of ​​the fiber-reinforced sheet 40 exceeds 2 kg / m2, the gaps between the fiber-reinforced plastic strands 43 become narrow. As a result, the binder 50 has difficulty passing between the fiber-reinforced plastic strands 43 of the fiber-reinforced sheet 40, which may result in poor application. For this reason, when using a fiber-reinforced sheet 40 with powder adhered thereto, it is preferable that the minimum gap between the fiber-reinforced plastic strands 43 in the powder-adhered state is more than the diameter of the strand 43 + 1 mm, and more preferably is equal to or greater than the diameter of the strand 43 + 1.5 mm.

[0046] The fiber-reinforced sheet 40 is a fiber-reinforced sheet in which a plurality of fiber-reinforced plastic strands 43 including reinforcing fibers 42 are aligned in the longitudinal direction and fixed to each other with a strand fixing material, and the strands 43 may be bundled into a belt shape, arranged with an interval of 3 to 5 mm between each belt, and fixed with the strand fixing material. The belt portion in which the strands 43 are bundled preferably has a width of about 5 to 50 mm, and other shapes and the like are similar to those of the fiber-reinforced sheet 43. The structure of the belt portion is not particularly limited, and it may be fastened using a wire fixing material, or may be fused using an adhesive.

[0047] An example of the reinforcing material may be a fiber-reinforced sheet in which a plurality of belt-shaped FRP plates (an example of fiber-reinforced plastic wires) containing reinforcing fibers 42 are arranged at equal intervals so as to be parallel to the longitudinal direction and the FRP plates are fixed to each other with a wire fixing material. The width of the belt-shaped FRP plate is preferably 10 to 50 mm, and the plate thickness and the intervals between the FRP plates are similar to those of the fiber-reinforced sheet using fiber-reinforced plastic wires 43.

[0048] As an example of the reinforcing material, a lattice material made of fiber-reinforced plastic may be used as shown in Fig. 11. The lattice material is formed by arranging a plurality of fiber-reinforced plastic wires 43 including reinforcing fibers 42 in a lattice pattern.

[0049] When forming a joint structure 94 in a lattice material made of fiber reinforced plastic, for example, plastic wires 43 protruding in one direction in a lattice shape at the end of the lattice material are placed between plastic wires 43 at the end of another lattice material made of fiber reinforced plastic.

[0050] As an example of the reinforcing material, a rod-shaped body made of fiber-reinforced plastic may be used. As the rod-shaped body, a fiber-reinforced plastic rod-shaped body containing reinforcing fibers 42 is used. A plurality of rod-shaped bodies can be arranged side by side for use.

[0051] <Each step of the reinforcement method> Hereinafter, each step of the reinforcing method, including the joint preparation step for preparing the joint structure 94, will be described.

[0052] <Surface preparation process> In the surface preparation step (see FIG. 3), a surface preparation step is performed to remove protrusions, attachments, deteriorated layers, and the like from the reinforced surface 90A of the structure 90. Removal of the protrusions, attachments, and deteriorated layers is performed using removal means such as a disk sander, sand blasting, steel shot blasting, and water jet. Note that the surface preparation step is not essential, and does not have to be performed.

[0053] <Primer application process> In the primer application step (see FIG. 4), a primer 20 is applied to a surface to be reinforced 90A of a structure 90. If a base preparation step has been performed, the primer 20 is applied to the surface to be reinforced 90A that has been subjected to base preparation.

[0054] A primer layer 22 made of the primer 20 is formed on the surface 90A of the structure 90 to be reinforced by the primer application step.

[0055] <Binder application process> The binder application step (see FIG. 5) is a step of applying a binder 50 to the reinforced surface 90A of the structure 90 to which the primer 20 has been applied.

[0056] By the binder application step, a binder layer 52 made of the binder 50 is formed on the reinforced surface 90A of the structure 90 to which the primer 20 has been applied (specifically, on the surface of the primer layer 22). The thickness of the binder layer 52 is at least thicker than the fiber-reinforced sheet 40, and is, for example, about 2 mm to 10 mm.

[0057] <Adhesion process> The bonding process is a process in which the fiber-reinforced sheet 40 is pressed against the applied layer of the binder 50 before the applied binder 50 hardens, thereby embedding the fiber-reinforced sheet 40 into the reinforced surface 90A of the structure 90. As a result, the fiber-reinforced sheet 40 is disposed inside the binder layer 52 of the binder 50.

[0058] The fiber reinforced sheet 40 is pressed with a roller or a rubber spatula, so that the air layer at the adhesive interface is expelled from the gaps between the fiber reinforced plastic strands 43, and the fiber reinforced sheet 40 is embedded and adhered to the binder layer 52.

[0059] <Joint creation process> In reinforcing the structure 90, since the area to be reinforced is generally larger than the dimensions of the fiber reinforced sheet 40, a joint structure 94 (see Figs. 7 to 9) is formed by overlapping the fiber reinforced sheets 40 by a predetermined length, and reinforcement is applied to the entire area that requires it. As shown in Figs. 7 to 9, the joint structure 94 is formed by overlapping two fiber reinforced sheets 40 such that the fiber reinforced plastic wires 43 of one fiber reinforced sheet 40 are disposed between the fiber reinforced plastic wires 43 of the other fiber reinforced sheet 40, and is bonded to the reinforced surface 90A (see Figs. 1 and 2) of the structure 90 by pressing them together with a roller or a rubber spatula. In the bonding process, the two fiber-reinforced sheets 40 may be overlapped in advance so that they are positioned between the wires 43, and then embedded and bonded in the binder layer 52. Alternatively, a thin layer of binder layer 50 may be applied, and then the two fiber-reinforced sheets 40 may be overlapped to form a joint portion 96, and the binder 50 may be applied from above to embed and bond the sheets.

[0060] <Finishing process> After the joint structure 94 is formed, the bonding material 50 is applied over the second overlapping sheet, the surface is smoothed, and a separate protective layer is formed as necessary.

[0061] <Effects of this embodiment> The effects of this embodiment will be described.

[0062] In the joint structure 94 of this embodiment, as shown in Figures 7 to 9, two fiber reinforced sheets 40 are stacked so that the fiber reinforced plastic strands 43 of one fiber reinforced sheet 40 are arranged between the fiber reinforced plastic strands 43 of the other fiber reinforced sheet 40, and are adhered to the reinforced surface 90A of the structure 90 (see Figures 1 and 2).

[0063] For this reason, as shown in Figures 12 and 13, the thickness of the joint portion 96 is reduced and the occurrence of steps on the outer surface of the joint portion 96 can be suppressed compared to when two plate-shaped reinforcing materials are stacked so that the fiber-reinforced plastic wires 43 of one fiber-reinforced sheet 40 and the fiber-reinforced plastic wires 43 of the other fiber-reinforced sheet 40 overlap in the thickness direction.

[0064] 9, in a joint structure 94 according to this embodiment, in a joint portion 96 where two fiber reinforced sheets 40 are overlapped, a distance L1 along the thickness direction between a cross-sectional center 43A of the fiber reinforced plastic strand 43 in one fiber reinforced sheet 40 and a cross-sectional center 43B of the strand in the other fiber reinforced sheet 40 is shorter than a thickness T40 of the fiber reinforced sheet 40. Therefore, compared to a case where the distance L1 is equal to or greater than the thickness T40 of the fiber reinforced sheet 40, the thickness of the joint portion 96 is reduced, and the occurrence of a step on the outer surface of the joint portion 96 can be suppressed.

[0065] In addition, in the joint structure 94 according to this embodiment, the distance between the fiber reinforced plastic strands 43 in the fiber reinforced sheets 40 is larger than the diameter of the fiber reinforced sheet 40. For this reason, it is possible to arrange the entire fiber reinforced plastic strands 43 in one fiber reinforced sheet 40 between the fiber reinforced plastic strands 43 in the other fiber reinforced sheet 40, thereby reducing the thickness of the joint portion and suppressing the occurrence of steps on the outer surface of the joint portion 96.

[0066] Furthermore, in the joint structure 94 according to this embodiment, the thickness of the wire fixing material 45 that fixes the fiber reinforced plastic strands 43 to each other is thinner than the diameter of the fiber reinforced plastic strands 43. Therefore, compared to when the thickness of the wire fixing material 45 is the same as the diameter of the fiber reinforced plastic strands 43, the thickness of the joint portion 96 is reduced, and the occurrence of steps on the outer surface of the joint portion 96 can be suppressed.

[0067] <Evaluation test> In this evaluation test, the effect of reducing the construction thickness, the reinforcing effect, and the adhesive strength of the joint structure 94 according to this embodiment were evaluated. Specifically, in this evaluation test, the following fiber-reinforced sheet 40 and binder 50 were used, and the evaluation test was performed on Examples 1 and 2 and Comparative Examples 1 and 2 as follows. [Fiber reinforced sheet 40] As the fiber-reinforced sheet 40, a sand-attached strand sheet (FSS-MM-450ME(C1) manufactured by Nippon Steel Chemical & Material Co., Ltd.), which is a fiber-reinforced sheet to which powder is attached, was used. FSS-MM-450ME(C1) is a single wire with a carbon fiber equivalent cross-sectional area of ​​2.0 mm 2 The average cross-sectional diameter of the wire, including the resin, is 2.2 mm, and the tensile strength of the wire converted to the cross-sectional area of ​​carbon fiber is 2900 N / mm 2 The elastic modulus is 4.0×10 5 N / mm 2 So, 1m 2 Carbon fiber usage per unit is 450g / m 2 The wires are installed at intervals of about 8 mm, and the gaps between the wires are about 5.4 mm. The fiber-reinforced sheet is then filled with 1 rin of Hakuryu crushed stone (average grain size 0.4 mm) for 1 m.2 The fiber-reinforced sheet is attached with epoxy resin adhesive at a ratio of 1 kg per fiber. The wire spacing in the sand-attached state is 4.80 mm (maximum) to 3.55 mm (minimum).

[0068] [Binding material 50] The binder 50 used was a high-toughness polymer cement mortar based on Refremolset D manufactured by Sumitomo Osaka Cement Co., Ltd., with the amount of reinforcing fiber, length of reinforcing fiber, aspect ratio of fiber (ratio of fiber diameter to length), type of fiber, and amount of water adjusted. This polymer cement mortar had a maximum fine aggregate diameter of 0.45 mm, an FM value of 1.02, and a W / P of 22.0 wt%. [Joint strength test and construction thickness evaluation] In this test, test pieces having the joint structure were prepared for Example 1 (shifted joint) and Comparative Example 1 (lap joint), and a joint strength test and an evaluation of the construction thickness were carried out. In addition, the weights of the test pieces for Example 1 and Comparative Example 1 were measured. The joint strength test was conducted to confirm whether the joint structure 94 according to this embodiment (Example 1) had the same reinforcing effect (joint strength) as a conventional joint structure (Comparative Example 1) in which wires were stacked in the thickness direction.

[0069] Example 1 In Example 1, the binder 50 was applied to a release film to a thickness of 12 mm over a section of 22.5 mm width and 320 mm length, and two of the fiber-reinforced sheets 40, each 12.5 mm wide and 410 mm long, were placed at the center and 7 mm from the top, offset so that a section of 300 mm from each end was positioned between the fiber-reinforced plastic strands 43, and embedded using a plastering trowel (see FIG. 14(A)). Furthermore, the above-mentioned bonding material 50 was applied to a thickness of 5 mm on top of that (see FIG. 14(B)). Thereafter, a release film was attached and the sheet was cured in a 20° C. environment for two weeks, and both ends of the fiber-reinforced sheet 40 were covered with epoxy resin (FB-E7S from Nippon Steel Chemical & Material Co., Ltd.) to prepare a test specimen (see FIG. 14(C)).

[0070] Comparative Example 1 In Comparative Example 1, the above-mentioned bonding material 50 was applied to a release film in a section of 22.5 mm width and 320 mm length to a thickness of 10 mm, and the above-mentioned fiber-reinforced sheet 40 of 12.5 mm width and 410 mm length as the first layer was embedded in the center and 5 mm from the top using a plastering trowel (see FIG. 15(A)). A second layer of fiber-reinforced sheet 40 of the same size as the first layer was prepared, and a portion 300 mm from its edge was placed directly on top of the portion 300 mm from its edge of the first layer of fiber-reinforced sheet (see Figure 15(B)). The bonding material 50 was then applied to the overlapping portion in a thickness of an additional 10 mm from above the fiber-reinforced sheet 40 using a plasterer's trowel, and construction was then performed (see Figure 15(C)). Thereafter, a release film was attached and the sheet was cured in a 20° C. environment for two weeks, and both ends of the fiber-reinforced sheet 40 were covered with epoxy resin (FB-E7S from Nippon Steel Chemical & Material Co., Ltd.) to prepare a test specimen (see FIG. 15(D)).

[0071] <Joint strength test> The joint strength test was performed by tensile testing of test pieces using a test method based on JSCE-E542-2013 Continuous fiber sheet joint test method (draft). Specifically, a universal material testing machine was used to perform the tensile test at a test speed of 4 mm / min, and the joint strength and ultimate state were visually observed. The results are shown in Table 1 in Figure 18. <Evaluation of construction thickness> In the evaluation of the construction thickness, the center of the joint part of the test piece (see line AA in FIG. 7) was cut using a diamond cutter, and the distance between the two joint layers of the fiber reinforced sheet 40 on the cut surface (see L1 in FIG. 9) and the shortest distance between the wires (see S1 in FIG. 9) were measured using a digital microscope. The results are shown in Table 1 in FIG. 18. [One-way shear test and evaluation of construction thickness] In this test, specimens having joint structures were prepared for Example 2 (shifted joint) and Comparative Example 2 (lap joint), and a single pull shear test and evaluation of construction thickness were performed. In addition, the weights of the specimens for Example 2 and Comparative Example 2 were measured. The one-way shear test was conducted to confirm whether the joint structure 94 (Example 2) according to this embodiment can obtain an adhesion strength (integrity between the fiber-reinforced sheet 40 and the concrete slab 98, which represents a concrete structure, which is an example of the object to be reinforced) equivalent to that of a conventional joint structure (Comparative Example 2) in which wires are stacked in the thickness direction.

[0072] Example 2 In Example 2, a JIS concrete slab 98 of 300 mm square was scraped and then coated with a water-based epoxy primer (FP-EE manufactured by Nippon Steel Chemical & Material Co., Ltd.), and the above-mentioned binder 50 was then applied to three locations with a width of 40 mm and a thickness of 7 mm (see FIG. 16(A)). Then, a fiber-reinforced sheet 40 cut to a width of 40 mm and a length of 300 mm was embedded and installed in each of the three locations (see FIG. 16(B)). Furthermore, three fiber-reinforced sheets 40 cut to a width of 40 mm and a length of 600 mm were prepared, and the wires of the sheets were pushed in so that the wires of the portions 300 mm from the ends were positioned between the wires of the first layer of fiber sheets (see FIG. 16(C)). After curing for two weeks in a 20°C environment, a test specimen was created by adhering a tab 99 made of epoxy resin and an aramid fiber sheet to one end of the 600 mm long fiber reinforced sheet 40 extending from a JIS concrete slab 98 (see Figure 16(D)).

[0073] Comparative Example 2 In Comparative Example 2, a JIS concrete slab 98 of 300 mm square was scraped, and then coated with a water-based epoxy primer (FP-EE manufactured by Nippon Steel Chemical & Material Co., Ltd.). Then, the above-mentioned binder 50 was applied to three places with a width of 40 mm and a thickness of 5 mm (see FIG. 17(A)). Then, a fiber-reinforced sheet 40 cut to a width of 40 mm and a length of 300 mm was embedded in each of the three places (see FIG. 17(B)). Furthermore, three fiber-reinforced sheets 40 cut to a width of 40 mm and a length of 600 mm were prepared as a second layer, and were stacked directly on top of the fiber-reinforced sheet 40 of the first layer. Furthermore, the binder 50 was applied to a thickness of 5 mm with a plastering trowel (see FIG. 17(C)). After curing for two weeks in a 20°C environment, a test specimen was created by adhering a tab 99 made of epoxy resin and an aramid fiber sheet to one end of the 600 mm long fiber reinforced sheet 40 extending from a JIS concrete slab 98 (see Figure 17(D)).

[0074] <One-way shear test> A one-way tensile shear test was performed on the test specimen using a universal testing machine and a test specimen fixing jig, and the integrity of the fiber-reinforced sheet 40 and the JIS concrete slab 98 (corresponding to structure 90) was evaluated based on the fracture load and fracture mode. The results are shown in Table 2 of FIG.

[0075] <Evaluation of construction thickness> In the evaluation of the construction thickness, the center of the joint part of the test specimen (see line AA in FIG. 7) was cut using a diamond cutter, and the distance between the two joint layers of the fiber reinforced sheet 40 on the cut surface (see L1 in FIG. 9) and the shortest distance between the wires (see S1 in FIG. 9) were measured using a digital microscope. The results are shown in Table 2 in FIG. 19.

[0076] [Evaluation Results] As shown in Table 1 of FIG. 18 and Table 2 of FIG. 19, the joint structure 94 (shifted joint) of this embodiment is thinner in construction thickness and lighter in weight than a conventional joint structure (lap joint) in which wires are overlapped in the thickness direction, yet has the same or greater reinforcing effect (joint strength) and adhesion strength (integrity between the fiber-reinforced sheet 40 and a concrete slab 98 representing a concrete structure, which is an example of an object to be reinforced). Therefore, by using the joint structure 94 (shift joint) according to this embodiment, it is possible to suppress the increase in thickness and weight due to reinforcement even in a long bridge, etc. In addition, the number of structures that can be constructed is increased compared to the conventional art, and the effectiveness of the present invention is clear.

[0077] The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0078] 20 Primer 22 Primer layer 40 Fiber Reinforced Sheet 42 Reinforced Fiber 43 Fiber-reinforced plastic wire 45 Wire fixing material 47 Matrix Resin 50 Binding material 52 Binder layer 90 Structures 90A Reinforced surface

Claims

1. Cross-sectional area 75mm ２ Two sheets of reinforcement material formed into a sheet shape with a plurality of wires of less than 1 mm spaced apart are overlapped so that the wires of one reinforcement material are placed between the wires of the other reinforcement material, and are bonded to the surface of the structure. Joint structure.

2. At a joint portion where the two reinforcing materials are overlapped, the distance in the thickness direction between the center of a cross section of the wire material in one reinforcing material and the center of a cross section of the wire material in the other reinforcing material is shorter than the thickness of the reinforcing material. The joint structure according to claim 1.

3. The spacing between the wires in the reinforcing material is greater than the diameter of the wires. The joint structure according to claim 1.

4. The reinforcing material is A fiber-reinforced sheet is made by arranging a plurality of fiber-reinforced plastic strands containing reinforcing fibers in a curtain-like shape in the longitudinal direction, and fixing the fiber-reinforced plastic strands to each other with a strand fixing material that is thinner than the diameter of the strands. The joint structure according to claim 1.

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