Anchoring structure and anchoring method

Abstract

The present invention addresses the problem of suppressing the progression of peeling of an FRP reinforcing material, even after a steel material yields, and maintaining a reinforcing effect achieved by the FRP reinforcing material. An anchoring structure in which a projection is inserted, via a hole in a perforated FRP reinforcing material, into a structure being reinforced to which the projection is fixed, and in which the structure being reinforced and the perforated FRP reinforcing material are integrated.

Description

Fixing structure and fixing method

[0001] The present invention relates to an anchoring structure and an anchoring method for a steel structure using FRP reinforcing materials.

[0002] Until now, FRP reinforcement using reinforcing fibers and thermosetting resins has been adopted mainly for existing reinforced concrete structures. In recent years, the need for repair and reinforcement of corrosion-deteriorated steel structures has increased, leading to an increase in the number of CFRP applications. In the case of corrosion-deteriorated steel structures, it is necessary to restore the rigidity lost by corrosion, so the number of layers tends to be much greater than in reinforced concrete structures.

[0003] Currently, the main fiber sheet reinforcement methods for steel structures are the hand layup method, which uses an impregnation roller to impregnate fiber reinforcement with resin on-site to form and bond FRP reinforcement, and the VaRTM (VaRTM) method, which uses Vacuum assisted Resin Transfer Molding (VaRTM) on-site to form and bond FRP reinforcement.

[0004] However, FRP reinforcements made using the hand layup method and the VaRTM method are both adhesively bonded, and as the number of fiber sheet layers that make up the FRP reinforcement that reinforces the steel structure increases, peeling of the FRP reinforcement occurs before the steel reaches yield. A method of tapering the ends of the FRP reinforcement has been proposed as a method to prevent peeling until the steel yields, but this method is unable to keep up with the elongation of the steel after yielding, causing the FRP reinforcement to peel rapidly, and does not lead to an improvement in the toughness of the steel.

[0005] On the other hand, there is a method of placing a resin with a low elastic modulus and good elongation between the steel and the FRP reinforcement, but this increases the length required to distribute the force generated in the steel to the FRP reinforcement, and it cannot follow the deformation of the steel after yielding, which can amount to several percent, so there is a limit to how much it can improve the toughness of the steel structure.

[0006] As mentioned above, adhesive bonding has its limitations, so it is possible to combine it with mechanical bonding. For example, Patent Document 1 proposes a structure and method for reinforcing existing bolted joints between steel materials with FRP, leaving the bolts in place. Also, Non-Patent Document 1 introduces a joining method in which an FRP base material and a steel plate are fastened together with bearing bolts or high-strength bolts.

[0007] Japanese Patent Application Laid-Open No. 2022-53653

[0008] Strength Experiments on Bearing Bolted Connections between Hybrid FRP Pultruded Members and Steel Members (Journal of the Japan Society of Civil Engineers, A1 (Structural and Earthquake Engineering), Vol. 76, No. 5, II_95‐II_104, 2020)

[0009] However, in Patent Document 1, the bolt portion of the joint protruding from the steel plate is removed, and only the body portion remains, but the body portion is not integrated with the FRP reinforcing material, and the FRP reinforcing material is integrated with the steel material by adhesive bonding. Therefore, it does not solve the problem that the present invention is concerned with.

[0010] Furthermore, in Non-Patent Document 1, when using bearing bolts to join an FRP base material and a steel plate, if the hole diameters of the FRP base material and the steel plate are not the same, the contact area between the FRP base material and the bearing bolts will decrease, resulting in a corresponding decrease in bearing strength. Furthermore, because actual structures are distorted due to unevenness, etc., when fastening an FRP base material with multiple bearing bolts, the hole diameter of the FRP base material must be larger than that of the bearing bolts; otherwise, the hole positions in the FRP base material and the steel plate will be misaligned, making it impossible to attach the FRP plate to the structure. When using high-strength bolts to frictionally join an FRP base material and a steel plate, creep occurs in the FRP plate over a long period of time, reducing the axial force of the high-strength bolts and resulting in a decrease in the friction force between the FRP plate and the high-strength bolts.

[0011] In view of the above, an object of the present invention is to suppress the progression of peeling of FRP reinforcing materials even after steel material yields, and to maintain the reinforcing effect of the FRP reinforcing materials.

[0012] In order to solve the above problems, the present invention employs the following configurations. [1] An anchoring structure formed by inserting the protrusions through the holes in a perforated FRP reinforcing material into a reinforced structure to which protrusions have been fixed, thereby integrating the reinforced structure and the perforated FRP reinforcing material. [2] The anchoring structure described in [1], wherein the protrusion width Dp [mm] and the hole diameter Df [mm] formed in the perforated FRP reinforcing material satisfy the relationship Df ≥ Dp. [3] The anchoring structure described in [2], wherein gaps between the holes formed in the perforated FRP reinforcing material and the protrusions are filled. [4] The anchoring structure described in [3], wherein the gaps are filled with either a primer or a matrix resin. [5] The anchoring structure described in [1], wherein the FRP reinforcing material is formed by impregnating a matrix resin with a plurality of laminated fiber-reinforced substrates made of reinforcing fibers. [6] The anchoring structure according to [5], characterized in that the fiber-reinforced substrate has reinforcing fibers aligned in one direction, and includes fiber-reinforced substrates in which the reinforcing fibers are oriented parallel to the main axis direction (0° direction) of the load acting on the reinforced structure, as well as fiber-reinforced substrates in which the reinforcing fibers are oriented at ±45° and 90° relative to the main axis direction. [7] The anchoring structure according to [5] or [6], characterized in that the fiber-reinforced substrate in which the reinforcing fibers are oriented at 90° is disposed in the outermost layer. [8] The anchoring structure according to [1], characterized in that the shape of the protrusion is any one of a cylinder, a threaded rod, a rivet, a bolt, or a rod with a polygonal cross section. [9] The anchoring structure according to [8], characterized in that the material of the protrusion is any one of plastic and metal.

[10] The anchoring structure according to [1], characterized in that the protrusion is fixed to the reinforced structure by any one of welding, screwing, or adhesive.

[11] The anchoring structure according to [1], characterized in that the center position of a cross section perpendicular to the axial direction of the protrusion is at a position at least twice the protrusion width Dp [mm] of the protrusion from the end of the FRP reinforcing material.

[12] The anchoring structure according to

[11] , characterized in that the distance between adjacent protrusions is at least twice the protrusion width Dp [mm].

[13] The anchoring structure according to [2], characterized in that the protrusion width Dp [mm] and the hole diameter Df [mm] satisfy the relationship 0≦Df-Dp≦5.

[14] The anchoring structure according to

[13] , characterized in that the protrusion contacts at least a portion of the hole provided in the perforated FRP reinforcement.

[15] The anchoring structure according to [5], characterized in that the resin bonding the protrusion, the reinforced structure, and the perforated FRP reinforcement is the matrix resin of the perforated FRP reinforcement.

[16] The anchoring structure according to

[15] , characterized in that at least a portion of the joint between the mechanical fastening portion of the perforated FRP reinforcement and the protrusion, centered on the perforated portion of the perforated FRP reinforcement, is convex with respect to the mechanical fastening portion of the perforated FRP reinforcement, and the thickness of the mechanical fastening portion of the perforated FRP reinforcement is thinner than the protruding portion of the protrusion.

[17] The anchoring structure according to

[15] , characterized in that at least a portion of the joint between the mechanical fastening portion of the perforated FRP reinforcement and the protrusion is coated with FRP reinforcement or a matrix resin.

[18] The anchoring structure according to

[16] or

[17] , characterized in that the number of layers of the mechanical fastening portion of the perforated FRP reinforcement is greater than the number of layers of the other FRP reinforcement.

[19] The anchoring structure according to

[15] , characterized in that the bearing strength of the mechanical fastening portion of the perforated FRP reinforcement is higher than the shear strength of the protrusion.

[20] An anchoring method comprising the steps of: fixing a protrusion to a structure to be reinforced; applying a primer at least around the protrusion; providing a hole in a laminate in which a fiber reinforcement base material has been previously laminated, inserting the protrusion into the hole and placing the laminate on the structure to be reinforced; and impregnating the fiber reinforcement base material with a matrix resin and curing the matrix resin to form an FRP reinforcement, characterized in that a gap exists between the hole and the protrusion, and the gap is filled with the matrix resin.

[21] A fixing method comprising the steps of applying a primer to the surface of a reinforced structure and laminating a fiber reinforcement substrate on the primer; impregnating the fiber reinforcement substrate with a matrix resin while hardening the matrix resin to form an FRP reinforcement material on the surface of the reinforced structure; and drilling holes in the FRP reinforcement material and the reinforced structure, inserting protrusions into the holes in the FRP reinforcement material, and fixing the protrusions to the reinforced structure, wherein a gap is formed between the hole and the protrusion, and the gap is filled with primer.

[22] The fixing method according to either

[20] or

[21] , characterized in that the reinforced structure and the protrusion are fixed by at least one of welding, screwing, and adhesive.

[23] The fixing method according to either

[20] or

[21] , characterized in that the impregnation of the fiber-reinforced substrate with the matrix resin is carried out by a vacuum impregnation molding method (VaRTM) or a hand lay-up method.

[0013] According to the present invention, the progression of peeling of the FRP reinforcing material can be suppressed even after the steel material has yielded, and the reinforcing effect of the FRP reinforcing material can be maintained.

[0014] FIG. 1 is a schematic diagram showing an example of an FRP reinforcing material according to an embodiment of the fixing structure of the present invention. FIG. 2 is a schematic diagram showing an example of an FRP reinforcing material according to an embodiment of the fixing structure of the present invention. FIG. 3 is a schematic diagram showing an example of a layering of fiber-reinforced substrates constituting the FRP reinforcing material according to the fixing structure shown in FIG. 1. FIG. 4 is a schematic diagram showing an example of a layering of fiber-reinforced substrates constituting the FRP reinforcing material according to the fixing structure shown in FIG. 2. FIG. 4 is a cross-sectional view showing an aspect in which protrusions are fixed to a reinforced structure. FIG. 5 is a plan view showing the positional relationship between an edge of a reinforced structure and protrusions. FIG. 6 is a plan view showing the positional relationship of protrusions continuously fixed to a reinforced structure. FIG. 7 is a plan view showing the positional relationship between hole diameters provided in a fiber-reinforced substrate and an edge of the substrate. FIG. 8 is a plan view showing the positional relationship of hole diameters continuously provided in a fiber-reinforced substrate and the positional relationship. FIG. 9 is a plan view showing the relationship between protrusion diameters and hole diameters provided in a fiber-reinforced substrate. FIG. 10 is a schematic diagram showing the positional relationship between protrusions and holes provided in a fiber-reinforced substrate, and showing (1) complete contact, (2) partial contact, and (3) no contact. FIG. 11 is a schematic diagram of protrusions coated with resin. This is a schematic diagram showing the protrusion, the mechanical fastening portion of the perforated FRP reinforcement, and its joint, and shows that (1) the joint has a convex shape relative to the mechanical fastening portion of the perforated FRP reinforcement, and (2) the joint is covered by the FRP reinforcement.

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] The present invention provides a fixing structure in which a reinforced structure to which protrusions are fixed is inserted through the holes in a perforated FRP reinforcement, integrating the reinforced structure and the perforated FRP reinforcement. This structure, compared to adhesive bonding alone, can suppress the progression of delamination of the FRP reinforcement even after steel yielding, thereby maintaining a stable reinforcing effect over a long period of time. Examples of reinforced structures include steel structures. As shown in Figures 1 and 2, a primer 40 is applied to the surface of the reinforced structure 10, and a perforated FRP reinforcement 30 is integrated thereon. The FRP reinforcement 30 has holes through which protrusions 20 are inserted. The FRP reinforcement around the protrusions may be thickened as shown in Figure 1, or the entire FRP reinforcement may have a uniform thickness as shown in Figure 2.

[0017] Here, it is preferable to apply a primer 40 to the surface of the reinforced structure 10. Applying the primer 40 can improve the adhesive strength between the FRP reinforcing material 30 and the reinforced structure 10. In this case, it is preferable to clean the surface of the reinforced structure 10 to remove rust and foreign matter from the reinforced structure 10 before applying the primer 40.

[0018] The FRP reinforcing material 30 is preferably formed by impregnating a matrix resin with a plurality of laminated fiber reinforcement substrates 31 to 34 made of reinforcing fibers. Figures 3 and 4 show an embodiment of the FRP reinforcing material 30 in which a plurality of fiber reinforcement substrates 31 to 34 are laminated.

[0019] Here, the fiber-reinforced substrate may be one having unidirectional reinforcing fibers or a woven fabric having multidirectional reinforcing fibers, etc., and may be used in appropriate combination. Among these, the use of unidirectional reinforcing fibers is preferred because it allows only the reinforcement required for the reinforced structure to be reinforced, which is economically rational.

[0020] The reinforcing fibers constituting the fiber-reinforced substrate are not particularly limited as long as they are reinforcing fibers that can be used in FRP, such as carbon fiber, glass fiber, and aramid fiber, but carbon fiber, which has excellent strength and elastic modulus, is preferred. The carbon fiber is not particularly limited, but polyacrylonitrile-based carbon fiber, rayon-based carbon fiber, and pitch-based carbon fiber are preferably used. Among these, polyacrylonitrile-based carbon fiber, which has high tensile strength, is particularly preferred. The carbon fiber may be in the form of twisted yarn, untwisted yarn, or non-twisted yarn.

[0021] When the carbon fibers constituting the fiber-reinforced substrate are in the form of a carbon fiber bundle, the number of filaments is not particularly limited. However, from the viewpoints of weaving productivity and the required tensile, compressive, and flexural moduli and strength of the FRP reinforcing material, the number of filaments in the carbon fiber bundle is preferably 1,000 to 70,000, and more preferably 1,000 to 60,000.

[0022] It is preferable that the width Dp [mm] of the protrusion 20 and the diameter Df [mm] of the hole 35 satisfy the relationship Df ≥ Dp. This allows the protrusions to be passed through the holes in the FRP reinforcing material when adhering the FRP reinforcing material to a structure to be reinforced via multiple protrusions, even if the structure is distorted due to unevenness or other reasons. Here, the width Dp [mm] of the protrusion 20 can be interpreted as the maximum diameter Dp [mm] of the protrusion 20. Furthermore, as shown in FIG. 11 , the positional relationship between the protrusion 20 and the hole 35 may be complete contact (1), at least partial contact (2), or complete separation (3). Of these, it is preferable that the protrusion 20 contacts at least a portion of the hole 35. This is to ensure that the load acting on the structure to be reinforced is transmitted to the FRP reinforcing material. Furthermore, when the projections 20 are spaced apart as shown in Figure (3), the gaps 36 between the projections 20 and the holes 35 are preferably filled with a primer 40 or the matrix resin impregnated into the fiber reinforcement substrates 31-34. Filling the gaps prevents the FRP reinforcement from peeling off before the load is transmitted to the projections, resulting in a more reliable reinforcement effect. Furthermore, filling the gaps with a primer or matrix resin further improves the integrity of the reinforced structure, the projections, and the FRP reinforcement, resulting in an excellent reinforcement effect.

[0023] The matrix resin used in FRP reinforcing materials may be either a thermosetting resin such as epoxy resin, vinyl ester resin, or urethane resin, or a thermoplastic resin such as nylon resin, polyphenylene sulfide resin, or polyether ether ketone resin, and the optimal resin is selected depending on the manufacturing method and required characteristics of the FRP reinforcing material.

[0024] The primer used in the present invention is not particularly limited, but two-component primers with excellent adhesive properties, such as epoxy primers, urethane primers, and acrylic primers, are preferred. Also, adhesives and the like with excellent adhesive properties to the reinforced structure 10 can be used as primers.

[0025] In addition to impregnating the fiber reinforced substrates 31 to 34 with the matrix resin, it is also possible to use prepregs in which the fiber reinforced substrates are pre-impregnated with the matrix resin.

[0026] The fiber-reinforced substrates preferably include a fiber-reinforced substrate 31 having a fiber orientation (0° direction) parallel to the main axis direction of the load acting on the reinforced structure 10, a fiber-reinforced substrate 32 having a fiber orientation (90°) perpendicular to the main axis direction of the load, and fiber-reinforced substrates 33 and 34 having fiber orientations (±45°) in the diagonal bracing direction. The number of layers of each fiber-reinforced substrate is preferably the largest for the fiber-reinforced substrate 31 parallel to the main axis direction of the load, followed by the fiber-reinforced substrates 33 and 34, and then the fiber-reinforced substrate 32. The order of layers is not particularly limited, but the fiber-reinforced substrate 32 is preferably the outermost layer.

[0027] Although fiber-reinforced substrates of the same size can be used as shown in Fig. 4, it is preferable to use fiber-reinforced substrates concentrated around the protrusions 20 as shown in Fig. 3. This is because it is possible to reinforce the load acting around the protrusions 20 and to optimize the amount of fiber-reinforced substrate used.

[0028] Of these, it is preferable that the fiber reinforcement substrate 32, in which the reinforcing fibers are oriented in a 90° direction, be arranged in the outermost layer of the FRP reinforcement material 30. This prevents the fiber bundles constituting the fiber reinforcement substrate 31 from separating when a load is applied to the FRP reinforcement material 30 in the 0° direction, and also prevents the FRP reinforcement material around the protrusions 20 from buckling in the thickness direction of the FRP reinforcement material. Furthermore, by adding a 45° layer, the load applied from the protrusions 20 can be dispersed and transmitted to the FRP reinforcement material, preventing abnormal failure due to stress concentration caused by the fiber direction or load direction, and achieving the designed bearing capacity.

[0029] The projections 20 are preferably either cylinders, threaded rods, rivets, bolts, or rods with polygonal cross sections. In the case of threaded rods 21, they can be screwed into holes that do not penetrate the reinforced structure 10, as shown in Figure 5 (1-1). It is also preferable to fix them in holes that penetrate the reinforced structure 10 so that they are exposed on both sides of the reinforced structure 10 (1-2). In the case of cylinders 22, they can be fixed by inserting them into holes that do not penetrate the reinforced structure 10 (2-1), or by welding them to the reinforced structure 10 (2-2).

[0030] The material of the protrusions 20 is preferably either plastic or metal, because the load acting on the reinforced structure 10 can be transmitted to the protrusions 20 accurately.

[0031] Furthermore, it is preferable that the protrusions 20 are fixed to the reinforced structure 10 by welding, screwing, or adhesive bonding. This is not only to increase the installation accuracy of the protrusions and FRP reinforcing material, but also to transmit the load acting on the reinforced structure to the FRP reinforcing material via the protrusions.

[0032] The center position of the cross section perpendicular to the axial direction of the protrusion 20 is preferably at least twice the width Dp [mm] of the protrusion 20 from the end of the FRP reinforcing material 30. If the protrusion 20 is too close to the end of the FRP reinforcing material 30, the bearing capacity of the FRP reinforcing material will not be exerted, and it will break under a low load.

[0033] Furthermore, when multiple protrusions 20 are arranged on the reinforced structure 10, the distance between adjacent protrusions 20 is preferably at least twice the width Dp [mm] of the protrusions 20. By providing a sufficient distance, excessive stress concentration around the protrusions can be prevented, and stable anchorage and reinforcement effects can be achieved.

[0034] The hole diameter Df [mm] of the holes 35 provided in the fiber reinforcement substrates 31 to 34 is preferably at least twice the hole diameter Df [mm] of the holes 35 from the ends of the fiber reinforcement substrates 31 to 34. When a plurality of protrusions 20 are arranged, it is preferable to provide a plurality of holes 35 in accordance with the positions of the protrusions 20.

[0035] It is preferable that the width Dp [mm] of the protrusion 20 and the diameter Df [mm] of the hole 35 satisfy the relationship 0≦Df−Dp≦5.

[0036] Next, the fixing method of the fixing structure according to the present invention will be described. There are two methods for carrying out the present invention.

[0037] The first method includes the steps of fixing the protrusions 20 to the reinforced structure 10, applying a primer 40 at least around the protrusions 20, providing holes 35 in a laminate in which fiber reinforcement substrates 31 to 34 have been previously stacked, inserting the protrusions 20 into the holes 35 and placing the laminate on the reinforced structure 10, and impregnating the fiber reinforcement substrate with a matrix resin and hardening the matrix resin to form an FRP reinforcement material 30, and is a fixing method characterized in that there is a gap 36 between the hole 35 and the protrusions 20, and the gap 36 is filled with the matrix resin.

[0038] The second method includes the steps of applying a primer 40 to the surface of the reinforced structure 10 and laminating fiber reinforcement substrates 31 to 34 on the primer 40, impregnating the fiber reinforcement substrate with a matrix resin while hardening the matrix resin to form an FRP reinforcement material 30 on the surface of the reinforced structure 10, and drilling holes in the FRP reinforcement material 30 and the reinforced structure 10, inserting protrusions 20 into the holes 35 of the FRP reinforcement material 30, and fixing the protrusions 20 to the reinforced structure 10, and is characterized in that there is a gap 36 between the holes 35 and the protrusions 20, and the gap 36 is filled with the primer 40.

[0039] In the first method, the protrusions 20 are first fixed to the reinforced structure 10, and then the fiber reinforcement substrates 31-34 are laminated. By doing so, even if the holes 35 interfere with the protrusions 20, the fiber reinforcement substrate around the holes 35 is deformed, allowing the protrusions 20 to pass through the holes 35. On the other hand, in the second method, the FRP reinforcing material 30 is formed on the reinforced structure 10, and then the holes are opened and the protrusions 20 are fixed thereto.

[0040] In the first method, if there is a gap 36 between the protrusion 20 and the hole 35, the matrix resin impregnated into the fiber reinforcement substrates 31 to 34 flows out and can be filled as is. On the other hand, in the second method, the matrix resin has already been impregnated, so the gap 36 can be filled with the primer 40. In this case, it is preferable to use the same type of primer 40 as the primer 40 applied to the reinforced structure 10.

[0041] Here, the impregnation of the matrix resin into the fiber reinforcement substrates 31 to 34 is preferably carried out by the vacuum impregnation molding method (VaRTM) or the hand lay-up method, because this method ensures reliable bonding and reduces the amount of air remaining in the FRP reinforcement material, thereby ensuring stable performance.

[0042] It is preferable that the reinforced structure 10, the projections 20, and the FRP reinforcing material 30 are bonded and integrated with the same matrix resin. By integrating them with the same matrix resin, there is no adhesive interface between the adhesives bonding the reinforced structure 10, the projections 20, and the FRP reinforcing material 30, thereby stabilizing the adhesive strength. However, to further improve the adhesive strength, a primer 40 may be applied to the reinforced structure 10, the projections 20, or both, before integration with the matrix resin. In this case, the matrix resin integrates the reinforced structure 10, the projections 20, and the FRP reinforcing material 30 via the primer.

[0043] It is preferable that at least a portion of the joint 61 between the perforated FRP reinforcement mechanical fastening portion 60 and the protrusion 20 has a convex shape relative to the perforated FRP reinforcement mechanical fastening portion 60, and that the thickness of the perforated FRP reinforcement mechanical fastening portion 60 is thinner than the protruding portion of the protrusion. Furthermore, it is more preferable that the joint 61 has a convex shape around the entire circumference. By making the joint convex, water generated by rainwater or condensation does not accumulate at the joint between the protrusion and the perforated FRP reinforcement mechanical fastening portion, but flows down, making it difficult for water to penetrate through the joint between the perforated FRP reinforcement mechanical fastening portion 60 and the protrusion 20, preventing corrosion of the protrusion 20 and the reinforced structure 10 due to water and reducing the adhesive strength of the joint 61.

[0044] It is preferable that at least a portion of the joint between the perforated FRP reinforcement mechanical fastening portion 60 and the protrusion 20 is coated with an FRP reinforcement material or a matrix resin. Furthermore, it is more preferable that the entire periphery of the joint 61 is coated with an FRP reinforcement material or a matrix resin. By coating the joint with an FRP reinforcement material or a matrix resin, it becomes difficult for water generated by rainwater or condensation to penetrate into the joint between the perforated FRP reinforcement mechanical fastening portion 60 and the protrusion 20, thereby preventing corrosion of the protrusion 20 or the reinforced structure 10 due to water and a decrease in the adhesive strength of the joint 61.

[0045] It is preferable that the number of layers of the perforated FRP reinforcement mechanical fastening portion 60 is greater than the number of layers of the other FRP reinforcement 30. By increasing the number of layers only of the perforated FRP reinforcement mechanical fastening portion 60, the compressive strength required to withstand the bearing pressure of the protrusions 20 can be ensured with the minimum necessary fiber reinforcement base material.

[0046] It is preferable that the bearing capacity of the perforated FRP reinforcement mechanical fastening portion 60 is higher than the shear capacity of the protrusions. Failure due to shear of the protrusions prevents the adhesive structure between the FRP reinforcement 30 and the reinforced structure 10 from being destroyed, making repairs easier. If the protrusions are made of metal, the plastic deformation of the protrusions absorbs energy, increasing the energy required for failure, which is more preferable.

[0047] The present invention can be applied to any existing steel structure or FRP structure where seismic reinforcement of steel structures or restoration or toughness improvement of corrosion-deteriorated steel structures is desired, and is particularly suitable for cases where easy on-site construction is desired.

[0048] 10 Reinforced structure 20 Protrusion 21 Threaded rod 22 Cylinder 30 FRP reinforcement 31 Fiber reinforcement substrate (0° sheet) 32 Fiber reinforcement substrate (90° sheet) 33 Fiber reinforcement substrate (+45° sheet) 34 Fiber reinforcement substrate (-45° sheet) 35 Hole 36 Gap 40 Primer 50 Direction of load acting on reinforced structure 60 Perforated FRP reinforcement mechanical fastening part 61 Joint Df Hole diameter Dp Protrusion width

Claims

1. A fixing structure in which the reinforced structure to which the protrusions are fixed is inserted through the holes in a perforated FRP reinforcing material, integrating the reinforced structure and the perforated FRP reinforcing material.

2. The anchoring structure described in claim 1, characterized in that the protrusion width Dp [mm] of the protrusion and the hole diameter Df [mm] of the hole provided in the perforated FRP reinforcing material satisfy the relationship Df ≧ Dp.

3. The anchoring structure according to claim 2, characterized in that the gap between the hole and the protrusion provided in the perforated FRP reinforcing material is filled.

4. The fixing structure according to claim 3, wherein the gap is filled with either a primer or a matrix resin.

5. The anchoring structure according to claim 1, characterized in that the FRP reinforcing material is made by laminating multiple fiber-reinforced substrates made of reinforcing fibers and impregnating them with a matrix resin.

6. The fixing structure described in claim 5, characterized in that the fiber-reinforced substrate has reinforcing fibers aligned in one direction, and in addition to the fiber-reinforced substrate in which the reinforcing fibers are oriented parallel to the main axis direction (0° direction) of the load acting on the reinforced structure, it also includes fiber-reinforced substrates in which the reinforcing fibers are oriented at ±45° and 90° relative to the main axis direction.

7. The fixing structure according to claim 5 or 6, characterized in that the fiber-reinforced substrate in which the reinforcing fibers are oriented at 90° is arranged in the outermost layer.

8. The anchoring structure according to claim 1, wherein the shape of the protrusion is one of a cylinder, a threaded rod, a nail, a rivet, a bolt, or a rod having a polygonal cross section.

9. The fixing structure according to claim 8, wherein the material of the protrusion is either plastic or metal.

10. The anchoring structure according to claim 1, wherein the protrusion is fixed to the reinforced structure by welding, screwing, or adhesive.

11. The anchoring structure described in claim 1, characterized in that the center position of the cross section perpendicular to the axial direction of the protrusion is at a position more than twice the protrusion width Dp [mm] of the protrusion from the end of the FRP reinforcement material.

12. The fixing structure according to claim 11, wherein the distance between adjacent protrusions is at least twice the protrusion width Dp [mm].

13. The fixing structure according to claim 2, wherein the projection width Dp [mm] and the hole diameter Df [mm] satisfy the relationship 0≦Df−Dp≦5.

14. The anchoring structure according to claim 13, characterized in that the protrusions are in contact with at least a portion of the holes provided in the perforated FRP reinforcing material.

15. The anchoring structure according to claim 5, wherein the resin that bonds the projection, the reinforced structure, and the perforated FRP reinforcing material is the matrix resin of the perforated FRP reinforcing material.

16. The anchoring structure described in claim 15, characterized in that at least a portion of the joint between the perforated FRP reinforcement mechanical fastening portion and the protrusion, centered on the perforated portion of the perforated FRP reinforcement, is convex in shape relative to the perforated FRP reinforcement mechanical fastening portion, and the thickness of the perforated FRP reinforcement mechanical fastening portion is thinner than the protruding portion of the protrusion.

17. The anchoring structure according to claim 15, wherein at least a portion of the joint between the perforated FRP reinforcement mechanical fastening portion and the protrusion is coated with the FRP reinforcement or matrix resin.

18. An anchoring structure as described in claim 16 or 17, characterized in that the number of layers of the mechanical fastening portion of the perforated FRP reinforcement is greater than the number of layers of the other FRP reinforcement.

19. The anchorage structure according to claim 15, wherein the bearing capacity of the mechanical fastening portion of the perforated FRP reinforcement is higher than the shear capacity of the protrusion.

20. A fixing method comprising the steps of: fixing a protrusion to a structure to be reinforced; applying a primer at least around the protrusion; forming holes in a laminate in which a fiber reinforcement substrate has been previously laminated, inserting the protrusion into the hole and placing the laminate on the structure to be reinforced; impregnating the fiber reinforcement substrate with a matrix resin and hardening the matrix resin to form an FRP reinforcing material, wherein a gap exists between the hole and the protrusion, and the gap is filled with the matrix resin.

21. A fixing method comprising the steps of applying a primer to the surface of a reinforced structure and laminating a fiber reinforcement substrate on the primer; impregnating the fiber reinforcement substrate with a matrix resin while hardening the matrix resin to form an FRP reinforcement material on the surface of the reinforced structure; and drilling holes in the FRP reinforcement material and the reinforced structure, inserting protrusions into the holes in the FRP reinforcement material, and fixing the protrusions to the reinforced structure, wherein a gap is formed between the hole and the protrusion, and the gap is filled with primer.

22. A fixing method according to claim 20 or 21, characterized in that the reinforced structure and the protrusion are fixed by at least one of welding, screwing, and adhesive.

23. The fixing method according to claim 20 or 21, wherein the impregnation of the matrix resin into the fiber-reinforced substrate is carried out by a vacuum impregnation molding method (VaRTM) or a hand lay-up method.

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