JP2015124553A - Method for repairing and reinforcing steel structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for repairing and reinforcing a steel structure in which a fiber sheet is bonded using an elastic putty material of high extensibility, and peeling of the fiber sheet may be prevented and the load transfer efficiency from the fiber sheet to steel members does not decline even at times of high stress and buckling deformation.SOLUTION: In a process (a) for surface preparation of a part on a steel member 10 to be worked, a process (b) for forming a putty layer (an elastic layer) 30 on the surface-prepared steel member 10 using a polyurea resin putty 30A, which is a putty material of high extensibility, and a process (c) for forming a plurality of fiber-reinforced resin layers 20 (20-1, 20-2, ...20-n) by laminating a plurality (n) of layers of fiber sheets 1a on the putty layer by bonding with a resin, the number of laminated fiber sheet layers (n) is determined to satisfy the following equation (1).

Description

  The present invention generally includes, for example, bridges, piers, chimneys, and the like using a sheet-like reinforcing fiber-containing material (hereinafter referred to as “fiber sheet”) including continuous reinforcing fibers, and also ships, vehicles, airplanes, etc. The present invention relates to a repair and reinforcement method for steel structures. More particularly, the present invention relates to a method for repairing and reinforcing a steel member subjected to an axial force and a vertical stress due to bending in a steel structure, and more particularly, to a steel structure that repairs or reinforces a corrosion-reduced steel member. It relates to repair and reinforcement methods.

  For example, steel structures such as steel bridges are corroded with service due to the effects of rainwater, incoming salt from the sea, and the scattering of antifreeze sprayed on the road surface.

  Most steel bridges have a girder structure of I-girder and box girder, and not only flange corrosion but also abdominal plate corrosion damage occurs due to water leakage at the end of the girder, ventilation and poor drainage.

  Conventionally, as a countermeasure in such a case, replacement of members using steel materials and patch plates have been common, but even if the repair scope is local, certain construction equipment and specialist engineers are required, and repairs are required. Expenses are extremely expensive.

  In Patent Document 1, as shown in FIG. 21 attached to the present application, an elastic layer 104 formed by applying and curing a polyurea resin putty agent on the surface of a steel structure (steel material) 100 is formed, and the elastic layer 104 is formed. A steel structure reinforcing structure 200 and a repair reinforcing method for forming a fiber sheet layer (fiber reinforced resin layer) 106 by bonding a fiber sheet 1 containing reinforcing fibers f to the surface of a steel structure 100 with an adhesive 105. Disclosure.

  Patent Document 2 is a steel member of a steel bridge 100 as shown in FIGS. 22 (a) and 22 (b) attached to the present application, and includes a belly plate 11, flanges 12 and 13, a stiffener 14 and When the fiber reinforced resin layer 20 is installed on the belly plate 11 in the steel girder 10 having the above, a putty layer 30 made of polyurea resin is provided between the steel girder belly plate 11 and the fiber reinforced resin layer 20, Thus, the ultimate load bearing capacity of the steel girder belly plate 10 is recovered and enhanced. That is, in the invention described in Patent Document 2, the steel member 10 is attached so that the fiber reinforced resin layer 20 is not peeled off and is subjected to a shearing force, that is, the seat of the belly plate 11 of the steel girder 10. It is intended to improve the yield strength.

International Publication Number WO2012 / 029966 JP 2012-52293 A

  On the other hand, for example, steel structures such as steel bridges are steel members such as main girders, cross girders, and vertical girder flanges that receive vertical stress due to bending, steel girder bridges, A member for receiving an axial force such as a string member of an truss bridge or an arch rib is provided.

  The inventors can effectively achieve the repair and reinforcement of the steel member by applying the techniques described in Patent Documents 1 and 2 to the steel member that receives the vertical stress due to the axial force and the bending. I could, but I found the following problems.

  In other words, according to the results of the present inventors' experiment, the steel member bonded with fiber reinforced resin (FRP) has a stress improvement effect according to the number of FRP layers, and is a high elongation elastic putty material. Adhesion of FRP through a certain polyurea resin putty material can surely prevent FRP peeling even at high stress or buckling deformation, but on the other hand, the load transmission efficiency from FRP to steel member can be reduced. I understood. Therefore, when the stress degree of a steel member is improved, if the cross section after FRP bonding is evaluated as a completely synthetic cross section of steel and FRP, the repair reinforcement amount is slightly insufficient.

  In view of this, the present inventors have found that the influence of the decrease in load transmission efficiency can be evaluated by multiplying the steel reduced cross-sectional area of the fiber sheet by the stress reduction coefficient Cn. The stress reduction coefficient Cn will be described in detail later.

  The present invention has been made based on such novel findings of the present inventors.

  An object of the present invention is to adhere a fiber sheet via a high elongation elastic putty material, thereby reliably preventing the fiber sheet from peeling even at high stress or buckling deformation, and the fiber sheet. Another object of the present invention is to provide a method for repairing and reinforcing a steel structure without reducing the load transmission efficiency from the steel member to the steel member.

The above object is achieved by the method for repairing and reinforcing a steel structure according to the present invention. In summary, the present invention relates to a steel structure in which a steel sheet subjected to an axial force and / or vertical stress due to bending in a steel structure is repaired and reinforced by bonding a fiber sheet containing reinforcing fibers with a resin. Repair and reinforcement method,
(A) a step of subjecting the construction target portion in the steel member to a ground treatment;
(B) a step of forming a putty layer with a polyurea resin putty material on the surface of the steel member subjected to the base treatment;
(C) On the putty layer, a plurality of (n) layers of the fiber sheets are bonded and laminated with a resin to form a plurality of fiber reinforced resin layers;
In a method for repairing and reinforcing a steel structure having
The fiber sheet lamination number (n) is determined so as to satisfy the following formula (1), and is a method for repairing and reinforcing a steel structure.

  According to one embodiment of the present invention, the fiber sheet of the plurality of layers is configured such that the length in the fiber direction decreases from the first layer on the surface side of the steel member to the n-th layer of the outermost layer. The ends in the fiber direction are shifted in steps by a predetermined amount and bonded.

  According to another embodiment of the present invention, the length in the fiber direction of the outermost n-th fiber sheet is made longer by the fixing length than the defect range in the construction target portion of the steel member.

  According to another embodiment of the present invention, the fixing length and the shift amount of the fiber sheet are increased as the tensile rigidity of the fiber sheet is increased.

  According to another embodiment of the present invention, the value of the stress reduction coefficient is decreased when the number of the laminated fiber sheets is increased, and is set to a constant value when the number of the laminated fiber sheets reaches a predetermined number.

  According to another embodiment of the present invention, the number of laminated fiber sheets at which the value of the stress reduction coefficient becomes a constant value is decreased as the fixing length and shift amount of the fiber sheet are increased.

  According to another embodiment of the present invention, the multiple-layer fiber sheet bonded to the construction target portion of the steel member is bonded to the first region of the construction target portion in the fiber direction of the fiber sheet. 1st multiple-layer fiber sheet which forms 1 fiber reinforced resin layer, and 2nd multiple-layer fiber sheet which adheres to the 2nd field of the above-mentioned construction object part, and forms the 2nd fiber reinforced resin layer In the region where the first and second fiber reinforced resin layers overlap each other, the first fiber reinforced resin layer and the second fiber reinforced resin layer are stacked and bonded together.

  According to another embodiment of the present invention, in the step portion formed in the construction target portion of the steel member, the first fiber reinforced resin is formed by bonding a plurality of layers of fiber sheets to the construction target portion excluding the step portion. In the region where the first and second fiber reinforced resin layers overlap each other, a second fiber reinforced resin layer is formed by bonding a plurality of fiber sheets to the construction target portion including the stepped portion. The second fiber reinforced resin layer is stacked on and adhered to the first fiber reinforced resin layer.

According to another embodiment of the present invention, the fiber sheet comprises:
(1) At least a fiber sheet in which reinforcing fibers including reinforcing fibers aligned in one direction along the sheet axial direction are fixed to each other with a wire fixing material,
(2) Is a fiber sheet in which a plurality of continuous fiber reinforced plastic wires that are impregnated with a matrix resin in a reinforced fiber and cured, are aligned in a slender shape in the longitudinal direction, and the wires are fixed to each other with a wire fixing material, Or
(3) A resin-impregnated cured fiber sheet obtained by impregnating a reinforcing fiber sheet in which reinforced fibers are aligned in one direction and the resin is cured, or a reinforcing fiber bundle aligned in one direction is impregnated with resin. A fiber sheet comprising at least one layer of a resin-impregnated cured fiber sheet obtained by curing the resin.

  According to another embodiment of the present invention, the reinforcing fiber of the fiber sheet includes inorganic fibers such as carbon fiber, glass fiber, and basalt fiber; metal fibers such as boron fiber, titanium fiber, and steel fiber; aramid, PBO (polyparaffin). (Phenylene benzbisoxazole), polyamide, polyarylate, polyester, and other organic fibers are used singly or in combination with a plurality of organic fibers.

  According to another embodiment of the present invention, the adhesive is a room temperature curable or thermosetting epoxy resin, epoxy acrylate resin, acrylic resin, MMA resin, vinyl ester resin, unsaturated polyester resin, phenol resin, or It is a photocurable resin.

  According to the present invention, the fiber sheet is bonded through the polyurea resin putty material, which is a high elongation elastic putty material, so that it is possible to reliably prevent the fiber sheet from peeling even during high stress or buckling deformation. Moreover, the load transmission efficiency from the fiber sheet to the steel member is not reduced.

1A and 1B show specific examples of steel members, FIG. 1A is a perspective view of a steel girder (steel I girder), and FIG. 1B is a truss member (box girder). FIG. FIGS. 2A, 2B, and 2C are diagrams illustrating a specific example of the repair and reinforcement mode according to the present invention. 3 (a) and 3 (b) are diagrams for explaining an example of the reinforcing structure of a steel member according to the present invention, FIG. 3 (a) is a front view of the steel member, and FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a view showing an embodiment of a fiber sheet that can be used in the steel structure repair and reinforcement method of the present invention. FIG. 5 is a view showing another embodiment of a fiber sheet that can be used in the steel structure repair and reinforcement method of the present invention. FIG. 6 is a perspective view showing another embodiment of a fiber sheet that can be used in the method for repairing and reinforcing a steel structure according to the present invention. 7 (a) and 7 (b) are cross-sectional views of fiber-reinforced plastic wires constituting a fiber sheet that can be used in the steel structure repair and reinforcement method of the present invention. FIGS. 8A and 8B are perspective views showing another embodiment of the fiber sheet that can be used in the steel structure repair and reinforcement method of the present invention. FIG. 9 is a process diagram for explaining an embodiment of a method for repairing and reinforcing a steel structure according to the present invention. FIG. 10 is a stress-strain curve diagram of a CFRP bonded steel sheet. FIG. 11 is a diagram of a study model for studying the stress-strain relationship of a CFRP bonded steel sheet. FIG. 12 is a diagram for explaining a stress-strain relationship of a CFRP bonded steel sheet. FIG. 13 is a diagram for explaining the relationship between the stress reduction coefficient Cn and the CFRP lamination number n. FIG. 14 is a diagram illustrating the CFRP fixing length and the shift amount in the steel structure repair and reinforcement method of the present invention. FIG. 15 is a diagram illustrating the fixing length and the shift amount when a strand type carbon fiber sheet is used. FIG. 16 is a cross-sectional view illustrating an embodiment of a mode in which carbon fiber sheets are connected by a lap joint. FIG. 17 is a cross-sectional view for explaining one embodiment of a CFRP connection mode in the vicinity of the splicing plate. 18 (a) and 18 (b) are views showing examples of CFRP pasting avoiding local unevenness, and FIGS. 18 (a) and 18 (b) are a plan view and a sectional view, respectively. 19 (a) and 19 (b) are cross-sectional views of a box girder and a steel I girder showing the relationship between the carbon fiber sheet adhesion width and the member corners, respectively. FIG. 20 is a cross-sectional view of a box girder illustrating a method for adjusting the number of laminated CFRPs by the repair and reinforcement method according to the present invention. FIG. 21 is a cross-sectional view of a reinforcing structure for explaining a conventional method for repairing and reinforcing a steel structure. 22 (a) and 22 (b) are a front view and a cross-sectional view, respectively, of a steel beam end portion of a steel bridge for explaining a conventional method for repairing and reinforcing a steel structure.

  Hereinafter, the steel structure repair and reinforcement method according to the present invention will be described in more detail with reference to the drawings.

Example 1
ADVANTAGE OF THE INVENTION According to this invention, the repair reinforcement of the steel member which receives the normal direction stress by an axial direction force and bending with a steel structure can be performed. For example, steel members subjected to axial force and vertical stress due to bending include steel girders (steel I girders) and truss members (box girders) used in steel bridges as shown in FIGS. 1 (a) and 1 (b). ) Etc. As shown in FIG. 1 (a), a steel girder 10 is formed of a belly plate 11 having an upper flange 12 and a lower flange 13, and a vertical stiffener 14 installed between the upper flange 12 and the lower flange 13. Is done. Moreover, the truss member 10 is formed by joining the four steel plates 15 (15a-15d), as shown in FIG.1 (b).

  For example, as shown in FIGS. 2 (a) and 2 (b), the steel girder 10 can repair and reinforce the upper surface or the lower surface of the lower flange 13, and the truss member 10 is shown in FIG. 2 (c). As shown, repair and reinforcement can be performed on the upper, lower, left, and right steel plates 15 (15a to 15d).

  In addition, the object (reinforcement object) of repair reinforcement | strengthening by this invention is not limited to the above steel structures and steel members, but this invention is the steel member which receives the vertical stress by an axial force and a bending. However, it can be applied effectively.

  FIG. 3 shows an example of a repair / reinforcement structure 50 in which a defect 40 generated in the lower flange 13 of the steel girder 10 according to the present invention is repaired and reinforced. As shown in this example, the lower flange 13 of the steel girder 10 thinned by corrosion is coated with a high elongation elastic putty material 30A after the base treatment, and then, with respect to this putty layer (elastic layer) 30, A sheet-like reinforcing fiber-containing material containing continuous reinforcing fibers, that is, a fiber sheet 1 (for example, a fiber sheet 1A shown in FIG. 4 to be described later) formed by adhering one or more layers with a resin. The (FRP) layer 20 (20-1, 20-2,... 20-n) is repaired and reinforced, and a protective layer 60 is provided on the outermost layer as necessary.

The features of the repair and reinforcement method for steel structures of the present invention are as follows:
A repair and reinforcement method for a steel structure in which a fiber sheet 1 containing reinforcing fibers f is bonded to a steel member 10 that is subjected to an axial force and / or vertical stress due to bending in the steel structure with a resin to repair and reinforce the steel member 10. There,
(A) a step of subjecting the construction target portion in the steel member 10 to a ground treatment;
(B) forming a putty layer (elastic layer) 30 with a polyurea resin putty material 30A, which is a high elongation elastic putty material, on the surface of the steel member 10 subjected to the base treatment;
(C) On the putty layer 30, a plurality (n) layers of fiber sheets 1 are bonded and laminated with a resin, and a plurality of fiber reinforced resin layers 20 (20-1, 20-2,... 20-n),
In a method for repairing and reinforcing a steel structure having
The number of layers (n) of the fiber sheets 1 is determined so as to satisfy the following formula (2).

  That is, according to the present invention, in the repair and reinforcement method for a steel structure in which the fiber sheet 1 is bonded to the steel member 10 via the polyurea resin putty material 30A (putty layer 30), the necessary cross-sectional area of the fiber sheets 1 to be laminated is obtained. Can be determined. At this time, when determining the necessary cross-sectional area of the fiber sheets 1 to be laminated, the loss of the reinforcing effect due to the insertion of the polyurea resin putty material 30A (putty layer 30) is compensated by introducing a stress reduction coefficient Cn. To be considered.

  Further, in the present invention, the fiber sheet 1 having a plurality of layers has a fiber direction length Ls that decreases from the first layer on the steel member surface side to the n-th layer of the outermost layer. The portions are bonded in a stepped manner by a predetermined amount Lm. Moreover, the fiber direction length of the fiber sheet 1 of the nth layer of the outermost layer is made longer by the fixing length Lf than the defect range (Lsl) of the defect part 40 in the construction target part of the steel member. Details will be described later according to the embodiment.

  Next, each material used in the present invention will be described.

(Fiber sheet)
In the present invention, various forms of fiber sheets 1 can be used. Although the Example of the fiber sheet 1 is concretely demonstrated as the specific examples 1-3, the form of the fiber sheet 1 used by this invention is not limited to what is shown to these specific examples.

Example 1
FIG. 4 shows an embodiment of the fiber sheet 1 that can be used in the present invention. In this embodiment, the fiber sheet 1 is a resin-unimpregnated fiber sheet 1A configured in a sheet shape by aligning continuous reinforcing fibers f in one direction.

That is, 1 A of fiber sheets can be set as the structure which hold | maintained the reinforcing fiber sheet which consists of the continuous reinforcing fiber f arranged in one direction with the wire fixing material 3 used as a mesh-like support body sheet | seat. For example, when carbon fibers are used as the reinforcing fibers f, for example, a plurality of unimpregnated single fiber bundles in which 6000 to 24000 single fibers (carbon fiber monofilaments) f having an average diameter of 7 μm are converged in parallel in one direction. Used to align. The fiber basis weight of the carbon fiber sheet 1A is usually 30 to 1000 g / m ² .

  Carbon obtained by impregnating the surfaces of the warp yarn 4 and the weft yarn 5 constituting the mesh-like support sheet as the wire fixing material 3 in advance with a low melting point type thermoplastic resin, and arranging the mesh-like support sheet 3 in a sheet shape The fibers are laminated on one or both sides of the fiber and heated and pressed to weld the warp 4 and weft 5 portions of the mesh-like support sheet 3 to the carbon fiber sheet.

  In addition to the biaxial configuration, the mesh-shaped support sheet 3 is formed by orienting glass fibers in three axes, or only the wefts 5 orthogonal to the carbon fibers arranged in one direction. It can also be bonded to the so-called uniaxially oriented carbon fibers that are arranged and aligned in the form of a sheet.

  As the yarn of the wire fixing material 3, for example, a double-structured composite fiber having a glass fiber in the core and a low-melting-point heat-fusible polyester around it is also preferably used. .

  In the above description, the reinforcing fibers f in the fiber sheet 1 have been described as being aligned in one direction along the sheet axial direction, but may be a fiber sheet in which the reinforcing fibers are oriented in two directions. It may be a woven fabric. However, the fiber sheet 1 includes at least reinforcing fibers aligned in the sheet axial direction.

Example 2
Further, as shown in FIG. 5, the fiber sheet 1 is obtained by impregnating a resin fiber with a reinforcing fiber sheet in which a plurality of reinforcing fibers f are aligned in one direction, for example, a fiber sheet 1A as shown in FIG. A fiber sheet (so-called FRP plate) 1B in which is cured.

  In the fiber sheets 1A and 1B described in the specific examples 1 and 2, the reinforcing fiber f is not limited to carbon fiber, but other than carbon fiber, inorganic fiber such as glass fiber and basalt fiber; boron fiber, Metal fibers such as titanium fiber and steel fiber; and organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, and polyester; Can be used.

  Further, as the resin Re in the case of the fiber sheet 1B in the specific example 2, a thermosetting resin or a thermoplastic resin can be used, and as the thermosetting resin, a room temperature curing type or a thermosetting type epoxy resin, Epoxy acrylate resins, vinyl ester resins, MMA resins, acrylic resins, unsaturated polyester resins, phenol resins, and the like are preferably used, and nylon, vinylon, and the like can be suitably used as the thermoplastic resin. The resin impregnation amount is 30 to 70% by weight, preferably 40 to 60% by weight.

  In the above description, the fiber sheet (FRP plate) 1B has been described as a reinforcing fiber sheet produced by aligning the reinforcing fibers f in one direction, for example, the fiber sheet 1A shown in FIG. A fiber sheet (FRP plate) obtained by impregnating a resin into a bundle of reinforcing fibers aligned in one direction by a pultrusion method or the like and then curing the sheet can also be used.

  In addition, as the resin-impregnated cured fiber sheet (FRP plate), a cloth or a mat layer is disposed on the surface of at least one FRP plate in which the reinforcing fibers (or reinforcing fiber bundles) as described above are aligned in one direction. It can be a laminate.

Example 3
Further, as shown in FIG. 6 and FIG. 7, the fiber sheet 1 has a plurality of continuous fiber reinforced plastic wires 2 having a small diameter and impregnated with a matrix resin R, and arranged in a slender shape in the longitudinal direction. A fiber sheet (strand-type fiber sheet) 1C in which the respective wire materials 2 are fixed to each other by the wire material fixing material 3 can also be used.

  The fiber reinforced plastic wire 2 has a substantially circular cross-sectional shape (FIG. 7A) having a diameter (d) of 0.5 to 3 mm, or a width (w) of 1 to 10 mm and a thickness (t) of 0. It can be a substantially rectangular cross-sectional shape (FIG. 7B) of 1 to 2 mm. Of course, other various cross-sectional shapes can be used as necessary.

  As described above, in the fiber sheet 1 </ b> C that is aligned and slid in one direction, the wires 2 are close to and separated from each other by a gap (g) = 0.05 to 3.0 mm. Fixed. The length (L) and width (W) of the fiber sheet 1 (1A, 1B, 1C) formed in this way are appropriately determined according to the size and shape of the structure to be reinforced, In general, the total width (W) is 100 to 1000 mm. Moreover, although the length (L) can manufacture a strip-shaped thing about 1-5 m, or a thing 100 m or more, it cuts and uses it suitably at the time of use. Moreover, it is also possible to manufacture the fiber sheet 1 (1A, 1B, 1C) with a length (L) of about 1 to 5 m and a width W of about 1 to 10 m.

  Also in the case of the fiber sheet 1C, the reinforcing fibers f include inorganic fibers such as carbon fibers, glass fibers, and basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; and further, aramid, PBO (polyparaphenylene). Benzbisoxazole), polyamide, polyarylate, polyester, and other organic fibers can be used alone or in a mixture of a plurality of organic fibers. The matrix resin R impregnated in the fiber reinforced plastic wire 2 can be a thermosetting resin or a thermoplastic resin. Examples of the thermosetting resin include a room temperature curable epoxy resin, a thermosetting epoxy resin, and an epoxy resin. An acrylate resin, a vinyl ester resin, an MMA resin, an acrylic resin, an unsaturated polyester resin, a phenol resin, or the like is preferably used, and nylon, vinylon, or the like can be preferably used as the thermoplastic resin. The resin impregnation amount is 30 to 70% by weight, preferably 40 to 60% by weight.

  Moreover, as a method of fixing each wire 2 with the wire fixing material 3, for example, as shown in FIG. 6, a plurality of wires arranged in a sled shape in one direction using wefts as the wire fixing material 3 are used. It is possible to adopt a method of driving and knitting a wire rod in the form of a sheet consisting of two, that is, a continuous wire rod sheet at a constant interval (P) perpendicular to the wire rod. The driving interval (P) of the weft yarn 3 is not particularly limited, but is usually selected in the range of 10 to 100 mm in consideration of the handleability of the produced fiber sheet 1.

  At this time, the weft 3 is, for example, a yarn obtained by bundling a plurality of glass fibers or organic fibers having a diameter of 2 to 50 μm. Moreover, nylon, vinylon, etc. are used suitably as an organic fiber.

  As another method of fixing each wire 2 in a slender shape, a mesh-like support sheet can be used as the wire fixing material 3 as shown in FIG.

  That is, the above-mentioned specific example in which a plurality of wire rods 2 arranged in the form of a sheet in a sheet form, that is, one side or both sides of a wire sheet is made of glass fiber or organic fiber having a diameter of 2 to 50 μm, for example. 1 may be configured to be supported by a mesh-like support sheet 3 having the same configuration as described in 1.

  Furthermore, as another method of fixing each wire 2 in a slender shape, as shown in FIG. 8 (b), as the wire fixing material 3, for example, a flexible belt material such as an adhesive tape or an adhesive tape is used. Can be used. The flexible strip 3 has one side or both sides of a plurality of fiber reinforced plastic wires 2 in a direction perpendicular to the longitudinal direction of each fiber reinforced plastic wire 2 arranged in the form of a sheet. Paste and fix.

  That is, as the flexible strip 3, an adhesive tape or adhesive tape such as a vinyl chloride tape, a paper tape, a cloth tape, and a nonwoven fabric tape having a width (w1) of about 2 to 30 mm is used. These tapes 3 are usually stuck in a direction perpendicular to the longitudinal direction of each fiber reinforced plastic wire 2 at intervals (P) of 10 to 100 mm.

  Furthermore, as the flexible strip 3, the thermoplastic resin such as nylon or EVA resin is formed into a strip and is heat-bonded to one side or both sides in the direction perpendicular to the longitudinal direction of the wire 2. Is done.

(Reinforcing method)
Next, a method for repairing and reinforcing a steel structure will be described with reference to FIGS. According to the present invention, the steel sheet can be repaired and reinforced using the fiber sheet 1 manufactured as described above.

  That is, according to the repair and reinforcement method for a steel structure of the present invention, for example, as the fiber sheet 1, the fiber sheet 1A produced by aligning the reinforcing fibers f described in the specific example 1 in one direction is used. This fiber sheet 1A is integrated by bonding with an adhesive via a putty layer (ie, elastic layer) 30 formed of a high elongation elastic putty material on the surface of the steel member 10 of the steel structure. Is done. At this time, simultaneously with the adhesion of the fiber sheet 1A to the steel member, the adhesive (matrix resin) impregnation of the fiber sheet 1A with this adhesive can also be performed.

  Thereby, the reinforcing structure 50 (refer FIG. 3 (a), (b)) which has the elastic layer 30 and the fiber sheet layer (fiber reinforced resin layer) 20 to which the fiber sheet 1A impregnated with resin is bonded is formed. The

  When reinforcing steel structures, for steel members (structures) that mainly receive bending moments and axial forces, the orientation direction of the reinforcing fibers is generally aligned with the principal stress direction of the tensile or compressive stress generated by the bending moment. By bonding, it is possible for the fiber sheet 1 to effectively bear the stress and to efficiently improve the load resistance of the structure.

  When bending moments act in two orthogonal directions, two or more fiber sheets 1 are orthogonally laminated and bonded so that the orientation direction of the reinforcing fibers f of the fiber sheet 1 substantially coincides with the principal stress generated by the bending moment. By doing so, the load bearing capacity can be improved efficiently.

  In the method for repairing and reinforcing a steel structure according to the present invention described below, as described above, the fiber sheet has the configuration shown in FIG. 4, and it is extremely preferable to use carbon fiber as the reinforcing fiber of the fiber sheet. Therefore, in this embodiment, a case where a unidirectional carbon fiber sheet is used as the fiber sheet 1 will be described. That is, in the description of the following examples, the fiber sheet 1 is described as a carbon fiber sheet, and the fiber sheet impregnated with resin, that is, the fiber reinforced resin (FRP) is described as a carbon fiber reinforced resin (CFRP). . However, the repair and reinforcement method of the present invention does not limit the reinforcing fibers to be used to carbon fibers, but can use other reinforcing fibers described above.

  The characteristics of the carbon fiber sheet suitably used in this example are as shown in Table 1 below.

An object of the repair and reinforcement method of the present invention is to increase the load resistance while preventing buckling as well as improving the steel material stress degree of the cross-sectional defect portion. According to the inventors' research experiments, in order to obtain these repair and reinforcement effects, the higher the elastic modulus of the carbon fiber sheet, the fewer the number of layers can be reduced, which is advantageous in terms of reducing the construction cost and shortening the construction period. I know that Therefore, in this example, it was standard to use a highly elastic carbon fiber sheet. The standard value of the elastic coefficient was set to 6.4 × 10 ⁵ N / mm ² or more, which is the maximum among the highly elastic carbon fiber sheets currently in circulation.

In this example, it was standard to use a carbon fiber sheet of 1900 N / mm ² or more. However, this is a member that is likely to buckle at the end, and the load resistance against buckling due to sufficient deformation of the steel material. This is because the use of a carbon fiber sheet having a low tensile strength and a low breaking strain may cause the carbon fiber to break due to bending during construction or the influence of local stress concentration.

In this example, it is standard that a unidirectional carbon fiber sheet having a fiber basis weight of 300 g / m ² is bonded in a required direction.

1. Ground treatment (S1)
The surface of the existing steel member 10 is freed from oil and dirt by removing the paint and rust by using an appropriate ground treatment method such as blasting or disc sander, and then cleaning the surface with an organic solvent. .

2. Primer application (S2)
In order to prevent rust on the surface of the steel material after the base treatment and to improve the adhesion between the carbon fiber sheet 1, a primer is applied. In general, a normal temperature curing type epoxy resin can be used as a primer.

3. Uneven correction (S3)
Since the flatness of the surface of the steel material affects the adhesion of the carbon fiber sheet 1, uneven areas after primer application such as steps and pitting portions are finished flat using a resin putty (non-land correction material) 40A.

  When the corner part (inner corner part) is molded using a resin putty, it is finished smoothly in an arc shape. In addition, the unevenness correcting material 40 </ b> A is not applied to the fixing portion of the carbon fiber sheet 1.

  The construction of this step S3 is performed after confirming that the primer applied in the above step S2 has been dry to the touch.

4). Primer application for high elongation elastic putty material (S4)
In order to improve the adhesiveness with the polyurea resin putty material used as the high elongation elastic putty material 30A, a primer for the polyurea resin putty material is applied to the surface of the steel material and the uneven surface of the uneven material. The construction is performed after confirming that the unevenness correcting material 40A applied in step S3 is initially cured.

  As a primer for a polyurea resin putty material, an epoxy-modified urethane resin primer can be suitably used. However, the primer is not limited to an epoxy-modified urethane resin, but a MMA-based resin such as a steel material or a non-land surface correction material, and a polyurea resin. A material that can sufficiently secure adhesiveness with the putty material is appropriately selected.

5. High elongation elastic putty material application (S5)
After applying the primer for the polyurea resin putty material in the step S4, the polyurea resin putty material 30A is applied to the affixing range of the carbon fiber sheet 1. The construction is performed after confirming that the primer for the polyurea resin putty material is dry to the touch. In addition, in order to achieve the required repair and reinforcement effects, apply as evenly as possible according to the design thickness.

  In general, the coating thickness (T) of the polyurea resin putty material 30A is appropriately set according to the unevenness of the surface to be bonded of the steel member 10 and the thickness of the carbon fiber sheet 1, but generally T = 0.2. 10 mm, and in this example, about 0.8 mm.

  The polyurea resin putty material as a high elongation elastic putty material 30A used in the present invention is a two-component (two-component mixed type) polyurea using an aromatic amine as a main material and an isocyanate prepolymer as a curing material. It is made of resin.

  The characteristics of the polyurea resin putty material preferably used in the present invention are as shown in Table 2 below.

  The high elongation elastic putty material 30 </ b> A (that is, the elastic layer 30) does not peel off the laminated carbon fiber reinforced resin (CFRP) 20 from the steel plate 10 even during out-of-plane deformation due to high stress or buckling. In order to demonstrate repair and reinforcement, the steel plate 10 and the CFRP 20 are joined.

  When the tensile modulus of elasticity of the high-elongation elastic putty material 30 is large, the CFRP 20 cannot sufficiently follow the deformation when the steel plate 10 is locally buckled and tries to deform out of plane. On the other hand, when the tensile elastic modulus is small, the CFRP 20 can follow the deformation of the steel plate 10, but the bonding effect of the CFRP 20 cannot be sufficiently obtained. If the maximum tensile load elongation of the high elongation elastic putty material 30A is small, the high elongation elastic putty material 30 breaks and the CFRP 20 peels when the steel plate 10 is greatly deformed by local buckling. If the elongation at the maximum tensile load is large, coexistence with the tensile elastic modulus is difficult.

  Therefore, in the present invention, a polyurea resin putty material having the characteristics shown in Table 2 is preferably used as the high elongation elastic putty material 30A.

  Further, the high elongation elastic putty material 30A loses rubber-like flexibility and becomes brittle at the glass transition temperature or lower, and cannot exhibit the required anti-peeling performance. Therefore, the upper limit of the glass transition temperature is set so that the required flexibility can be maintained even in a low temperature environment in winter. The steel material adhesive strength is the same as that for other resin materials (adhesives).

6). Carbon fiber sheet bonding (S6)
When it is confirmed that the polyurea resin putty material 30A is initially cured, the carbon fiber sheet 1 is bonded onto the elastic layer 30 formed of the polyurea resin putty material 30A. An example of the carbon fiber sheet bonding construction procedure is as follows.

In the present invention, the vertical stress of the steel girder flange, which is the steel member 10, and the axial force of the truss chord material are generally based on the fiber direction being the member axial direction because the principal stress direction coincides with the member axial direction. And
(1) The impregnated adhesive resin is uniformly applied to the construction surface with a roller brush.
(2) The carbon fiber sheet 1 is pressed against the application surface of the impregnated adhesive resin, and is attached while removing bubbles in the fiber direction.
(3) A bubble roller or a rubber spatula is used to remove air pockets, and the carbon fiber sheet 1 is sufficiently impregnated with the impregnated adhesive resin.
(4) On the bonded carbon fiber sheet 1, the impregnated adhesive resin is uniformly applied again with a roller brush, and the impregnated adhesive resin is sufficiently impregnated so as not to cause harmful floating and swelling.

The impregnation adhesive resin, that is, the adhesive has been described as being applied onto the polyurea resin putty material 30A (elastic layer 30), but of course, it can also be applied to the carbon fiber sheet 1, and the polyurea resin You may apply | coat on both the surfaces of the putty material 30A (elastic layer 30) and the adhesion surface of the carbon fiber sheet 1.
(5) When two or more carbon fiber sheets 1 are laminated, the operations (1) to (4) are repeated.
(6) The end shift amount Lm in the longitudinal direction of the carbon fiber sheet 1 is performed in the following manner.

  That is, as described in the above (5), when the necessary amount of reinforcement is large, it is possible to bond a plurality of layers of carbon fiber sheets 1 to the surface of the structure. When the layers are laminated and bonded, stress concentration occurs at the end portion, and the peel fracture resistance may be lowered.

  Therefore, in order to prevent peeling failure, it is preferable to change the sheet length Ls in the fiber direction of the carbon fiber sheet 1 of each layer as shown in FIGS. 3 and 14. For example, the length Ls in the fiber direction of the carbon fiber sheet 1 to be laminated in a plurality of layers becomes shorter in order toward the outer layer (the outermost carbon fiber sheet) that is separated from the surface of the steel member 10 (the first carbon fiber sheet). And the edge part 1a of the carbon fiber sheet 1 is laminated | stacked on step shape. The shift amount (Lm) of the end 1a is suitably about 5 mm to 100 mm.

  That is, by reducing the length (Ls) of the carbon fiber sheet 1 to be laminated in a plurality of layers by about 5 to 100 mm in order from the outer layer and laminating the end 1a in a stepped manner, the stress concentration at the sheet end 1a is reduced. It is possible to improve the peeling resistance.

  The length Ls, the fixing amount (Lf), and the shift amount (Lm) of the carbon fiber sheet 1 will be described in detail later.

Next, a resin (adhesive) that is impregnated into the carbon fiber sheet and impregnated with the carbon fiber sheet.
Will be described.

  The carbon fiber sheet 1 exhibits strength and elastic modulus as a composite material of fibers and resin (CFRP) in a state where the resin is satisfactorily impregnated between the fibers. The impregnated adhesive resin must be able to ensure the adhesive strength with the steel material 10, the tensile strength of the carbon fiber sheet 1, and the joint strength.

  The impregnating adhesive resin used in this example is a two-component (two-component mixed type) room temperature curing type epoxy resin. The physical properties of the epoxy resin used in this example are as shown in Table 3 below.

  The adhesive that can be used in the present invention includes thermosetting epoxy resins, epoxy acrylate resins, acrylic resins, MMA resins, vinyl ester resins, unsaturated polyester resins, in addition to the above room temperature curing type epoxy resins. Phenol resin or photo-curing resin is suitable.

7). Adhesion of protective layer (S7)
If necessary, a two-way aramid fiber sheet can be applied as the protective layer 60 of the fiber sheet 1 (see FIG. 3).

  For example, when a carbon fiber sheet is used as the fiber sheet 1 as in the present example, it is confirmed that the carbon fiber sheet is excellent in durability by an outdoor exposure test or an accelerated exposure test. However, the impregnated adhesive resin is deteriorated by the action of ultraviolet rays or ozone, and may be discolored such as whitening or yellowing to impair the appearance. Moreover, since a carbon fiber sheet is black and surface temperature rises when it receives direct sunlight, it is preferable to construct a protective work so as not to exceed the heat resistance temperature of the resin.

  Since the aramid fiber sheet used for the protective layer 60 of the carbon fiber sheet 1 is bent at the corners, a bi-directional material is used. Aramid fibers have excellent impact resistance and are flexible, so that they can be wound around member corners. In particular, it is effective to wrap a steel member having a box-shaped closed section such as a truss chord material or an arch rib. Furthermore, the function of the carbon fiber sheet protective layer in the future repainted keren can be achieved.

8). Curing (S8)
Until the impregnated adhesive resin is initially cured, it is cured with a vinyl sheet or the like as needed to prevent adhesion of rainwater, sand, dust, etc., and to avoid adverse effects due to sudden changes in weather.

9. Finish painting (S9)
The aramid fiber sheet used for the protective work in the step S7 is preferably subjected to surface protection coating because ultraviolet deterioration occurs due to organic fibers.

  By performing the steps S1 to S9 according to the repair and reinforcement method of the present invention, a reinforcing structure 50 for the steel member 10 is obtained as shown in FIGS.

That is, according to the present embodiment using the carbon fiber sheet 1, the carbon fiber sheet 1 is bonded to the steel member 10 that receives the axial force and / or the vertical stress due to bending in the steel structure with a resin. 10 is a method for repairing and reinforcing a steel structure for repair and reinforcement,
(A) a step of subjecting the construction target portion in the steel member 10 to a ground treatment;
(B) a step of forming a putty layer 30 with a polyurea resin putty material 30A on the surface of the steel member 10 subjected to the base treatment;
(C) On the putty layer 30, a plurality of (n) layers of carbon fiber sheets 1 are bonded and laminated with a resin, and a plurality of carbon fiber reinforced resin layers (CFRP) 20 (20-1, 20-2, ... 20-n),
A method for repairing and reinforcing a steel structure having the above is implemented.

The necessary cross-sectional area Asl for repair and reinforcement of the steel member is determined so as to be equal to or larger than the cross-sectional area of the steel member due to corrosion and the sum of the steel member stress levels calculated under the following conditions is within the allowable stress level.
(1) The dead load already acting before CFRP adhesion is borne by the existing steel cross section.
(2) Live load and dead load acting after CFRP adhesion are borne by the combined cross section of steel and CFRP.

  However, when the amount of cross-sectional defects due to corrosion is local and slight, or when the target is a secondary member, the cross-sectional area of the steel member may be set as the necessary cross-sectional area for repair and reinforcement Asl, and the stress level check may be omitted.

  In addition, in order to avoid the sudden change of the cross section due to corrosion and to restore the performance, it is based on the fact that CFRP corresponding to the defective cross section is pasted and the stress level of the steel member is checked in consideration of the load state before and after the CFRP adhesion. The strength of the carbon fiber sheet is much higher than that of the steel material, and since there is no problem in terms of stress, the verification may be omitted. In addition, when the cross-sectional defect | deletion by corrosion is also local and minor also in secondary members, such as an anti-tilt structure and a horizontal structure, stress degree verification may be abbreviate | omitted in consideration of the simplicity of repair design. The case where the amount of cross-sectional defect is small can be considered as the case where the number of laminated CFRP corresponding to the defect cross-sectional area is about 5 or less.

  In the repair and reinforcement method for a steel structure according to the above embodiment, the necessary cross-sectional area Asl for repair and reinforcement of the steel member is calculated, and the required number n of CFRP layers is determined. In addition, since the elastic modulus of the resin is about 1/100 or less of the elastic modulus of the carbon fiber and the volume ratio of the resin is 70 to 80%, the influence of the resin on the tensile stiffness of the entire CFRP is about 5%. It is. Therefore, it is possible to calculate the cross-sectional area of only the carbon fiber sheet in the calculation of CFRP.

It has been confirmed that the steel material to which CFRP is bonded can obtain a stress improving effect according to the number of laminated layers of CFRP. Further, as described above, according to the present invention, the high elongation elastic putty material (polyurea resin putty material) 30A (elastic layer 30) having an elastic modulus of about 65 N / mm ² (about 1/3000 of steel material) is provided. The carbon fiber sheet 1 can be surely prevented from being peeled even during high stress or buckling deformation. On the other hand, the load transmission efficiency from the carbon fiber sheet 1 to the steel member 10 is reduced. For this reason, when improving the stress degree of a steel member, if the cross section after carbon fiber sheet adhesion | attachment is evaluated as a complete synthetic cross section of the steel member 10 and the carbon fiber sheet 1, the amount of repair reinforcement will be somewhat insufficient.

  Therefore, in the present invention, the influence of the decrease in the load transfer coefficient is evaluated by multiplying the stress reduction coefficient Cn by the steel equivalent cross-sectional area Acf, s of the carbon fiber sheet. The necessary cross-sectional area Asl for repair and reinforcement of the steel member is calculated, and the necessary number n of CFRP layers is determined.

  That is, the number n of stacked carbon fiber sheets is determined so as to satisfy the following formula (3).

  As described above, since the load transmission effect to the carbon fiber sheet 1 is reduced when the number n of carbon fiber sheets is increased, the stress reduction coefficient Cn corresponding to the number n of layers is multiplied. The stress reduction coefficient Cn is set based on experimental results and numerical analysis results. This point will be described in more detail later.

  Further, the design thickness tcf of the carbon fiber sheet is obtained by the following equation (4).

In the case of the carbon fiber sheet (Ecf = 640 kN / mm ² , fiber basis weight w = 300 g / m ² , ρ = 2.1 × 10 ⁶ g / m ³ ) using the high elastic carbon fiber used in this example. The design thickness per one carbon fiber layer is tcf = 0.143 mm, and the steel equivalent thickness tcf, s = 0.457 mm. Therefore, if the carbon fiber sheet width Bcf is determined, the steel equivalent cross-sectional area Acf, s of the carbon fiber sheet is obtained.

  In this way, the necessary cross-sectional area Asl for repair and reinforcement of the steel member is calculated, and the necessary number of CFRP layers is determined.

  Here, as the design thickness tcf of the carbon fiber sheet, the cross-sectional area of only the carbon fiber is used as described above. That is, the elastic modulus of the resin is about 1/100 or less of the elastic modulus Ecf of the carbon fiber when the reinforcing fiber is a carbon fiber as in this embodiment, and the volume ratio of the resin is 70 to 80%. Therefore, the influence of the resin on the tensile stiffness of the entire CFRP is about 5%. Therefore, the cross-sectional area of the carbon fiber sheet 1 is used for calculation of CFRP. The cross-sectional area of the resin is not expected in the design.

It has been confirmed that the steel material bonded with CFRP can obtain a stress improvement effect corresponding to the number of laminated layers of CFRP. However, in the method of the present invention, the elastic modulus is about 65 N / mm ² (about 1/3000 of the steel material). The high elongation elastic putty material (polyurea resin putty material) is applied to the adhesive layer. This makes it possible to reliably prevent CFRP from being peeled off even during high stress or buckling deformation. The load transmission efficiency is reduced (see FIG. 10). For this reason, when improving the stress degree of a steel member, if the cross section after CFRP adhesion is evaluated as a completely synthetic cross section of steel and CFRP, the amount of repair reinforcement will be slightly insufficient.

  In view of this, in the present invention, the influence of the decrease in load transmission efficiency is evaluated by multiplying the stress reduction coefficient Cn by the steel equivalent cross-sectional area Acf, s of the carbon fiber sheet 1.

  Since the load transmission efficiency changes according to the fixing length Lf and the CFRP lamination number n, the stress reduction coefficient Cn can be set based on the uniaxial tensile test and numerical analysis result of the CFRP bonded steel sheet.

Next, the characteristic of the “stress reduction coefficient Cn” that characterizes the present invention will be described.
(About stress reduction factor)
In setting the stress reduction coefficient Cn, a uniaxial tensile test and numerical analysis were performed on the CFRP bonded steel sheet shown in FIG. 11 using the CFRP lamination number n, the fixing length Lf, and the shift amount Lm of each layer as parameters. Numerical analysis methods are as follows: “Takeshi Miyashita and Masami Nagai: Stress analysis of steel sheets laminated with multi-layer CFRP subjected to uniaxial tension, JSCE A, Vol. 66 (2010), No. 2, pp. 378-392. ”Was used.

Representative examples of the stress-strain relationship at the point of interest are shown in FIGS. 12 (a), 12 (b), and 12 (c). From this result, it is understood that when the fixing length Lf and the shift amount Lm of each layer are insufficient, the load transmission efficiency is significantly reduced. Moreover, it turns out that rigidity starts to fall compared with a numerical calculation result from the steel plate stress vicinity of 150-200 N / mm < ² >. This is considered to be due to the softening of the putty layer 30 (putty material 30A), but the stress level due to the dead load generated on the actual bridge is about 150 N / mm ² at the maximum (with respect to the allowable stress level of SM570 material of 255 N / mm ²⁾ . In this example, the load transmission effect was evaluated by the numerically calculated rigidity.

Next, the results of organizing the stress reduction coefficient Cn using the number n of layers as a parameter are shown in FIGS. 13 (a), (b), and (c). From this result, the following matters can be confirmed about the load transmission efficiency from the steel plate 10 to CFRP.
(1) The influence of the fixing length Lf is extremely large, and the load transmission efficiency is greatly improved by setting the fixing length (Lf) from 100 mm to 200 mm.
(2) The influence of the shift amount Lm is also relatively large. In particular, when the number n of layers is large, the load transmission efficiency to the CFRP becomes good by securing the shift amount (Lm) of 25 mm.
(3) The influence of the number n of layers reacts relatively sensitively at the stage where the number of layers is small, but even if a minimum value is given in any of about 5 to 15 layers and then the number n of layers increases, the stress reduction coefficient The value of Cn hardly changes.

In other words, from the above,
1. The fixing length Lf and the shift amount Lm of the fiber sheet 1 are increased when the tensile rigidity of the fiber sheet 1 is increased.
2. The value of the stress reduction coefficient Cn is reduced when the number n of the fiber sheets 1 is increased, and is constant (0.25 to 0) when the number n of the fiber sheets 1 reaches a predetermined number (any one of 5 to 15). .8).
3. The number n of fiber sheets 1 at which the value of the stress reduction coefficient Cn becomes a constant value is decreased as the fixing length Lf and the shift amount Lm of the fiber sheet 1 are increased.
I will do it.

  In view of the above, considering the load transmission efficiency by CFRP adhesion and simplicity in practical design, in this embodiment, as shown in FIG. 14, the fixing length (Lf) is 200 mm and the shift amount (Lm) is 25 mm as a standard structure. The stress reduction coefficient Cn was set to a value shown in Table 4 while setting as fine.

  In addition, it confirmed by numerical analysis that the difference in the plate | board thickness of the steel member (base material) 10, the usage-amount of an impregnation adhesive resin material, and the thickness of the unevenness correction material 40A has little influence on load transmission efficiency. However, for the thickness of the high elongation elastic putty material (polyurea resin putty material) 30A (elastic layer 30), the value of the stress reduction coefficient Cn was set in consideration of a construction error of 10%.

The stress reduction coefficient Cn shown in Table 4 is the structure of the adhesion cross section obtained by the repair and reinforcement method according to the construction procedure of the present invention described with reference to FIG. 9, and the structural details shown in FIG. Assuming that 200 mm and the shift amount Lm satisfy 25 mm, a highly elastic carbon fiber sheet (design value of elastic coefficient: 6.4 × 10 ⁵ N / mm 2, fiber basis weight: 300 g / m 2) Application is limited when used. For this reason, when using carbon fiber sheets with different elastic coefficients and fiber basis weights, other values are set for the value of the stress reduction coefficient Cn.

  For example, as another embodiment, numerical analysis is performed on the structural details and the stress reduction coefficient Cn when the so-called strand-type carbon fiber sheet 1C described as the carbon fiber sheet 1 with reference to FIGS. 6 to 8 is used. Figure 15 and Table 5 show the results calculated by the examination using

  Next, the length Ls and the fixing length Lf of the carbon fiber sheet 1 will be described.

  The length Lcf of the carbon fiber sheet 1 in the fiber direction is determined so as to satisfy the following formula (5).

  In other words, the carbon fiber sheet 1 having a plurality of layers has a length in the fiber direction that is shortened from the first layer on the steel member surface side to the nth layer on the outermost layer, and the end of the carbon fiber sheet 1 in the fiber direction is located. Glue in a staircase step by step. Further, the fiber direction length Ls of the nth carbon fiber sheet of the outermost layer is made longer by the fixing length Lf than the defect range Lsl in the construction target portion of the steel member.

  More specifically, in this embodiment, as understood from the result of the examination of the load transmission efficiency Cn to the CFRP described above, when the carbon fiber sheets 1 having a plurality of layers are laminated and bonded, the fixing length Lf Secure 200 mm or more. Avoid the uneven surface as much as possible in the fixing part, and if it is unavoidable, smooth the surface with the unevenness correction material 40A and extend the CFRP adhesion length to ensure a fixing length Lf of 200 mm or more on the smooth steel girder surface. To do. The unevenness correction of the fixing unit will be described later.

  The bonded end is bonded by shifting the fiber sheet by 25 mm for each layer in the member axial direction (see FIG. 14).

  Since the stress is concentrated on the bonded end portion, it becomes a starting point from which the CFRP peels. Therefore, the carbon fiber sheet is shifted and bonded in the main stress direction for the purpose of relaxing the stress concentration. The shift amount Lm is ensured by changing the length of the carbon fiber sheet for each layer. In addition, the unevenness due to the cross-sectional defect and the end of the defect range are smoothed as much as possible to avoid stress concentration, and then corrected for unevenness.

  With reference to FIG. 16, the case where the carbon fiber sheet 1 is connected in the fiber axis direction by the joint portion 70 will be described.

  Referring to FIG. 16, in this example, the multiple-layer fiber sheet bonded to the construction target portion of the steel member is bonded to the first region of the construction target portion in the fiber direction of the fiber sheet, and the first A first multi-layer fiber sheet that forms the fiber reinforced resin layer 20A; a second multi-layer fiber sheet that forms a second fiber reinforced resin layer 20B by adhering to the second region of the construction target portion; In the region where the first and second fiber reinforced resin layers 20A and 20B overlap, the first fiber reinforced resin layer 20A and the second fiber reinforced resin layer 20B are overlapped and bonded, 70 is formed.

  In the present embodiment, the lap joint length Lt in the fiber direction in the joint portion 70 is set to a minimum value of 100 mm. In addition, when connecting the carbon fiber sheet 1 of a several layer, it adhere | attaches by adhering an adhesive end 25 mm for every layer.

  In the joint test of the high-elasticity carbon fiber sheet, it has been confirmed that if the lap joint length Lt is 100 mm, the steel member (base material) 10 is destroyed without breaking at the joint portion 70. Therefore, the minimum value of the joint length Lt is set to 100 mm. It is not necessary to provide a lap joint because no stress is transmitted in the direction perpendicular to the fiber.

  Further, as shown in FIG. 17, a splicing plate 17 is joined to the lower flange 12 of the steel girder. For this reason, the carbon fiber sheet 1 is continuous in the main stress direction in the vicinity of the splicing plate 17 or the like. It may be difficult to paste.

  In this case, as shown in the drawing, in the step portion formed in the construction target portion of the steel member, the first fiber reinforced resin layer 20A is formed by bonding a plurality of fiber sheets to the construction target portion excluding the step portion. Forming a second fiber reinforced resin layer 20B by adhering a plurality of fiber sheets to a construction target portion including a stepped portion, and overlapping the first and second fiber reinforced resin layers 20A and 20B Then, the second fiber reinforced resin layer 20B is stacked on the first fiber reinforced resin layer 20A and bonded to form a joint portion.

More specifically, different fiber sheets 1A and 1B can be bonded to the flange portion 13 and the attachment plate 17, respectively. In this case, in order to prevent the separation of the carbon fiber sheets 1A and 1B at the step portion, the carbon fiber sheets 1A and 1B are gently molded with the unevenness correcting material 40A with a gradient of 10 times or more the step height tp _{+ b} , and the carbon fiber is formed at the flat portion. The sheets 1A and 1B are wrapped and connected. The wrap length Lp is set to 100 mm or more in consideration of the stress transmission length with the steel member 12, and when connecting a plurality of layers of carbon fiber sheets, the adhesive end is shifted by one layer (Lm) to prevent peeling. ) Adhere by 25mm.

  Further, when CFRP is fixed to a portion with unevenness such as the bolt part Bt, as shown in FIGS. 18 (a) and 18 (b), the unevenness is corrected smoothly using the unevenness correcting material 40A. The CFRP bonding length can be extended with a smooth steel surface to ensure the required fixing length. When the range of the unevenness is limited, it is preferable to study a method of bonding the FRP while avoiding the uneven portion by gently bending a part of the fiber. In this case, the rubbing length Lb is preferably about 1:10.

  Moreover, as shown in FIG. 19, it is as follows if the precautions at the time of repairing and reinforcing the steel member 10 by further laminating a carbon fiber sheet are raised.

  The width of the carbon fiber sheet in the direction perpendicular to the fiber is such that Lb = 5 mm or more from the edge in the width direction of the member, and the carbon fiber sheet is not bonded to the corners (protruding corners and entering corners) of the member. In order to reduce the number of layers, it is preferable to make the width of the fiber sheet as large as possible.

  In addition, the carbon fiber sheet is not bonded at the corners (entering corners and exiting corners) because defective construction such as bubbles and swelling is likely to occur. Further, it is preferable to adhere slightly from the edge of the member in consideration of workability during the base treatment, primer application, and impregnation adhesion.

  When the required number of sheets increases and it is difficult to construct the damaged steel plate surface, the bonding positions may be dispersed within the same cross section as shown in FIG. In other words, if there are nine layers of CFRP 20 to be attached to the steel plate 15c, three layers of CFRP 20 can be applied to the steel plate 15c, and three layers can be dispersed and attached to the other steel plates 15a, 15b, 15c.

  As described above, various experiments have shown that a stress improvement effect can be obtained by performing such affixing even for an extreme corrosion form in which a part of the member penetrates due to local pitting corrosion. It has been confirmed. For this reason, also in this invention, a sticking position can be adjusted so that the average stress as a member can be improved. In FIG. 20, the example of the adjustment method of the lamination | stacking number of the carbon fiber sheets 20 is shown for the chord material of the truss bridge as the steel member 10.

  In the present embodiment, in the repair and reinforcement method for a steel structure of the present invention, the case where carbon fiber is used as the reinforcing fiber of the fiber sheet 1 has been described. However, the reinforcing fiber used in the repair and reinforcement method of the present invention is carbon. It is not limited to fibers, and other reinforcing fibers described above can be used. Also in this case, as understood from the above description, the stress reduction coefficient Cn depends on the type of reinforced fiber, the fixing length, the shift amount, and the number of FRP laminations, and the uniaxial tensile test and numerical analysis results of the FRP bonded steel sheet Can be set based on.

DESCRIPTION OF SYMBOLS 1 Fiber sheet 10 Steel member 11 Abdominal plate 12, 13 Flange 14 Stiffener 20 Fiber reinforced resin layer 30 Putty layer 30A Polyurea resin putty material (high elongation elastic putty material)
40A Unevenness correction material 40 Deficient part 50 Reinforcement structure 70 Lap joint

Claims (13)

A steel structure repairing and reinforcing method for repairing and reinforcing the steel member by adhering a fiber sheet containing reinforcing fibers to a steel member subjected to an axial force and / or vertical stress due to bending in the steel structure,
(A) a step of subjecting the construction target portion in the steel member to a ground treatment;
(B) a step of forming a putty layer with a polyurea resin putty material on the surface of the steel member subjected to the base treatment;
(C) On the putty layer, a plurality of (n) layers of the fiber sheets are bonded and laminated with a resin to form a plurality of fiber reinforced resin layers;
In a method for repairing and reinforcing a steel structure having
The number of laminated fiber sheets (n) is expressed by the following formula (1),

A method of repairing and reinforcing a steel structure, characterized in that it is determined so as to satisfy   The multi-layer fiber sheet has a length in the fiber direction that decreases from the first layer on the surface side of the steel member to the n-th layer on the outermost layer, and steps in the fiber direction of the fiber sheet by a predetermined amount. The method of repairing and reinforcing a steel structure according to claim 1, wherein the bonding is performed by shifting the shape of the steel structure.   3. The repair of a steel structure according to claim 2, wherein a length in a fiber direction of the fiber sheet of the nth layer of the outermost layer is made longer by a fixing length than a defect range in a construction target portion of the steel member. Reinforcement method.   The method for repairing and reinforcing a steel structure according to claim 3, wherein the fixing length and the shift amount of the fiber sheet are increased when the tensile rigidity of the fiber sheet is increased.   5. The steel structure according to claim 4, wherein the value of the stress reduction coefficient is set to be small when the number of the fiber sheets stacked is increased, and is set to a constant value when the number of the fiber sheets stacked reaches a predetermined number. How to repair and reinforce things.   6. The repair of a steel structure according to claim 5, wherein the number of laminated fiber sheets at which the value of the stress reduction coefficient becomes a constant value decreases as the fixing length and shift amount of the fiber sheets increase. Reinforcement method.   The plurality of fiber sheets bonded to the construction target portion of the steel member are bonded to the first region of the construction target portion in the fiber direction of the fiber sheet to form a first fiber reinforced resin layer. A first multi-layer fiber sheet, and a second multi-layer fiber sheet that forms a second fiber reinforced resin layer by adhering to a second region of the construction target portion, and the first The first fiber reinforced resin layer and the second fiber reinforced resin layer are overlapped and bonded in an overlapping region of the second fiber reinforced resin layer. Repair and reinforcement method for steel structure according to item.   In the step part formed in the construction target part of the steel member, a first fiber reinforced resin layer is formed by bonding a plurality of fiber sheets to the construction target part excluding the step part, and includes the step part. A second fiber reinforced resin layer is formed by adhering a plurality of fiber sheets to a construction target portion, and the second fiber reinforced resin layer is formed in an overlapping region of the first and second fiber reinforced resin layers. The method for repairing and reinforcing a steel structure according to any one of claims 1 to 6, wherein the first fiber reinforced resin layer is laminated and bonded.   9. The fiber sheet according to claim 1, wherein the fiber sheet is a fiber sheet in which reinforcing fibers including at least reinforcing fibers aligned in one direction along a sheet axial direction are fixed to each other with a wire fixing material. Repair and reinforcement method for steel structure as described in the section.   The fiber sheet is a fiber sheet in which reinforced fibers are impregnated with a matrix resin, and a plurality of cured continuous fiber reinforced plastic wires are aligned in a slender shape in the longitudinal direction, and the wires are fixed to each other by a wire fixing material. A method for repairing and reinforcing a steel structure according to any one of claims 1 to 8.   The fiber sheet is a resin-impregnated cured fiber sheet obtained by impregnating a resin in a reinforcing fiber sheet in which reinforcing fibers are aligned in one direction, or a resin in a reinforcing fiber bundle in which the resin is aligned in one direction. 9. The repair and reinforcement of a steel structure according to claim 1, wherein the steel structure is a fiber sheet including at least one layer of a resin-impregnated cured fiber sheet in which the resin is cured. Method.   Reinforcing fibers of the fiber sheet include inorganic fibers such as carbon fibers, glass fibers, and basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; aramids, PBO (polyparaphenylene benzbisoxazole), polyamides, polyarylates The method of repairing and reinforcing a steel structure according to any one of claims 1 to 11, wherein organic fibers such as polyester are used alone or in a hybrid mixed with a plurality of types.   The adhesive is a room temperature curing type or thermosetting type epoxy resin, epoxy acrylate resin, acrylic resin, MMA resin, vinyl ester resin, unsaturated polyester resin, phenol resin, or photocurable resin. The method for repairing and reinforcing a steel structure according to any one of claims 1 to 12.

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