JP4857032B2 - Steel structure reinforcing method and reinforcing structure - Google Patents

Description

  The present invention relates to a method for reinforcing a steel structure such as a bridge or an elevated road, and a reinforced steel structure. In addition, the reinforcement mentioned here includes not only repair reinforcement caused by corrosion of steel members in the existing steel structure, but also improvement reinforcement that strengthens the existing structure to support higher loads. Shall also be included.

  As a means for reinforcing a steel structure such as a bridge, a method of attaching a steel material to a necessary portion on an existing steel member by welding or a bolt is well known. However, according to such a construction method, it is necessary to heat the existing steel member or to make a bolt hole, which causes a decrease in strength, and the attached steel material that cannot be easily constructed. In recent years, a reinforcement method using a carbon fiber resin plate has been proposed as having the disadvantage that the weight of itself becomes a burden on the steel structure.

Patent Document 1 below relates to such a reinforcing method, in which a plurality of carbon fiber reinforced resin plates having a predetermined strength and a predetermined shape are previously overlapped with an adhesive and bonded to the lower surface of a steel member of the bridge with an adhesive. Propose that. That is, a plate obtained by bonding about 6 layers of carbon fiber resin plates having a thickness of 1.2 mm (to a thickness of about 8 mm) is joined to a steel member of a bridge as shown in FIG. 8, thereby reinforcing the bridge. . Since a large bending moment works in the vicinity of the center of the beam, the number of bonded resin plates is increased in the vicinity of the center.
JP 2003-193425 A

  When a carbon fiber resin plate that has been hardened in advance as a plate having a thickness of several millimeters or more as shown in Patent Document 1 is bonded to a bridge or the like, the surface of the steel member is used during the use of the steel structure. The resin plate is expected to be easily peeled off. In general, the Young's modulus of carbon fiber resin is considerably higher than the Young's modulus of steel members. Therefore, when a plate having a thickness exceeding 1 mm is used, the rigidity is significantly different from that of steel members. Because it will end up.

  For example, in the bridge (steel structure 1) shown in FIG. 3 (a), the carbon fiber resin plate 10 is bonded to the lower surface (b portion, etc.) of the steel member 2 as shown in FIG. Let us consider a case where a tensile force (for example, a tensile force based on a bending moment) is applied. A horizontal shearing force H acts on the bonding surface between the steel member 2 and the carbon fiber resin plate 10 based on the difference in rigidity between the steel member 2 and the carbon fiber resin plate 10, and the horizontal shearing force H is in the direction of the tensile force. It peaks at the end 11 of the resin plate 10. When a plate having a thickness exceeding 1 mm is bonded as described above, the peak value at the end becomes extremely large as shown by the curve b1 in FIG. Easy to exceed peel strength.

  Based on the above points, the claimed invention provides a method for reinforcing a steel structure that can easily and effectively reinforce a steel structure and is difficult to cause separation of a reinforcing material even under load. Is.

The method for reinforcing a steel structure described in the claims is to overlap and bond a plurality of reinforcing fiber sheets on the surface of a steel member in the steel structure, and to force (tensile force or compressive force) of the reinforcing fiber sheets. It is characterized in that a treatment for dispersing the horizontal shearing force generated on the adhesive surface is applied to the end in the acting direction.
“Reinforcing fiber sheet” refers to a sheet (non-resin-impregnated sheet) in which reinforcing fibers such as carbon fibers (carbon fibers, long fibers) are made into thin cloth-like sheets. The reinforcing fibers may be arranged in one direction or may be a sheet-like woven fabric that is not.
“Adhesion” of the reinforcing fiber sheet means that the above-described sheet is bonded onto the surface of a steel member or the like together with an impregnation adhesive (such as an epoxy resin). As the bonding procedure, for example, an impregnation adhesive is applied to a corresponding portion of the surface of a steel member, a reinforcing fiber sheet is stacked before it solidifies, and an impregnation adhesive is further applied thereon before solidifying, and a roller or the like. Is used to infiltrate the impregnated adhesive between the fibers, flatten the surface, and wait for the adhesive to solidify. Since a plurality of reinforcing fiber sheets are bonded, such a procedure is repeated to bond the reinforcing fiber sheets together.

According to the above reinforcing method, the reinforcing fiber sheet used as the reinforcing material is unlikely to peel off. Similar to the conventional technique (Patent Document 1), a reinforcing material having a high Young's modulus called a reinforcing fiber sheet is bonded to the surface of the steel member, but it is not a pre-laminated and solidified plate (carbon fiber resin plate). The thin sheet 20 as shown in (b2) is used, and the horizontal shearing force generated on the adhesive surface is distributed to the end portion 21 (the end portion in the direction in which the force acts. B portion in FIG. 3A) of the sheet 20. It is because the treatment for making it take place. When the thin sheet 20 is bonded in this way, the horizontal shearing force H acts between the sheet 20 and the steel member 2 as shown in the figure based on the difference in Young's modulus, but the peak shearing force generated at the end of the sheet 20. For example, H is dispersed and becomes a small value as shown by a curve b2 in FIG. If the peak value of the shearing force H in the vicinity of the end portion becomes small, the possibility that the sheet peels from the steel member starting from the end portion is also reduced.
Since this method is not a method of joining steel materials by bolts, nuts, or welding, this reinforcement method does not cause a decrease in strength due to the processing of bolt holes or the thermal effect of welding, and increases the weight burden on the steel structure. There is also a merit that the construction is simple and easy.

Especially about the reinforcement method of invention, it is good to adhere | attach several reinforcing fiber sheets on the surface of the steel member in a steel structure so that an edge part may overlap in steps in the direction where force acts.
The state where "the end overlaps stepwise" here means that the end of the sheet on the outer side (the side far from the steel member) does not protrude from the end of the inner sheet (the side closer to the steel member). A state in which a plurality of sheets are stacked with the positions shifted. However, the end of each sheet does not necessarily deviate so as to form one step of the staircase, and the end may coincide between some sheets. In addition, each reinforcing fiber sheet shall adhere | attach on the whole surface in contact with a steel member or an inner reinforcing fiber sheet.

  If the end portions of the reinforcing fiber sheet are shifted in a stepped manner and overlapped as described above, peeling of the reinforcing fiber sheet adhered to the surface of the steel member can be appropriately prevented. When the end portion 21 of the sheet 20 is shifted and overlapped as in the example of FIG. 3 (b2), the horizontal shearing force H acting between the sheet 20 and the steel member 2 is as shown by the curve b2 in FIG. 3 (c). This is because it is dispersed and the peak value near the end becomes small.

  About the reinforcement method of invention, it is also preferable to attach to the edge part of the said reinforced fiber sheet | seat by adhere | attaching the cover sheet which covers it on the surface of a steel member, and the edge part of a reinforced fiber sheet | seat. The ends of the reinforcing fiber sheets may be overlapped in a stepped manner as described above, but may be overlapped so that the ends of all (all layers) sheets coincide.

  About a reinforced fiber sheet, peeling can be effectively prevented by overlapping an edge part in steps as mentioned above. However, even in such a case, when the load or deformation of the steel structure increases and the sheet reaches the limit at which peeling occurs, the end in the direction in which the tensile force acts is always the starting point of peeling. Therefore, if the cover sheet covering the end of the reinforcing fiber sheet is bonded to the surface of the steel member and the end as described above, and the end is fixed by the cover sheet, the peeling of the reinforcing fiber sheet is prevented. Is more effective with respect to However, even if the ends of the reinforcing fiber sheets are stepped, and the ends of all the sheets coincide with each other, the effect of preventing peeling is brought about in the same manner as the cover sheets are attached in this way.

  Further, the end of the outer sheet may protrude from the end of the inner sheet at the end in the direction in which the force acts, and the end of the protruded sheet may also be bonded to the surface of the steel member. FIGS. 7A and 7B are diagrams illustrating such a case.

Even when the end of the outer sheet protrudes from the end of the inner sheet and is adhered to the surface of the steel member, the effect of preventing the sheet from peeling off from the steel member can be obtained. This is because the ends of the sheets do not coincide with each other, so that the horizontal shearing force acting between the sheet and the steel member is dispersed and the peak value is also reduced.
Since the end of the sheet that overlaps the outside covers the end of each inner sheet and is bonded to each end of the inner sheet and the surface of the steel member, the end of the outer sheet is attached to the above-described cover sheet. It will also play a role. Therefore, if it does in this way, the effect that it becomes unnecessary to attach a cover sheet will also be brought about.
Of the ends of the reinforcing fiber sheet in the direction in which the force acts, one end is overlapped in a stepped manner (for example, as shown in FIG. 3 (b2)), and the other end is the end of the outer sheet. The part may stick to the surface of the steel member or the like so as to protrude from the end of the inner sheet (for example, as shown in FIG. 7B). In that case, it becomes possible to make the length of the reinforcing fiber sheet to be used repeatedly overlapped.

Regarding the above-mentioned reinforcement method,
・ Use a reinforcing fiber sheet with a thickness of 0.9 mm or less,
-It is preferable that the position of the end of each reinforcing fiber sheet in the direction in which the tensile force acts is shifted by 25 mm or more in the direction in which the tensile force acts. The way of shifting the position of the end of each sheet is to shift so that the end of the outer sheet protrudes (adheres the protruding end to the surface of the steel member) Also good.

When a reinforcing fiber sheet having a high Young's modulus is used as a reinforcing material, a large horizontal shearing force acts on the end of the sheet as described above when a plate-like or a thick sheet close thereto is used. Even when thin sheets are used, horizontal shearing force tends to concentrate on the edges if the edges of many sheets are matched. In that respect, as described above, when the thickness of the reinforcing fiber sheet is 0.9 mm or less and the end is shifted by 25 mm or more for each sheet, according to the inventors' investigation, the steel member and the reinforcing fiber sheet There is no peak shear force that exceeds the normal bond strength between. That is, under the above conditions, peeling of the reinforcing fiber sheet hardly occurs.
Compared to the case of using a thick hard sheet or plate, it is easier to carry out construction work such as transportation, cutting, and adhesion by using a thin sheet with a thickness of 0.9 mm or less and being easy to deform, In addition, it is easy to closely adhere to a steel member or the like in an existing steel structure steel member (thus generating vibration or the like with use).

Regarding the reinforcing method of the invention, the steel material having a cross-sectional area obtained by multiplying the cross-sectional area of the reinforcing fiber sheet by the Young's modulus ratio of the steel sheet and the steel structure is changed to the original steel member. It is appropriate to predict that they are integrated. The above Young's modulus ratio is
Young's modulus ratio = Young's modulus of reinforcing fiber sheet / Young's modulus of steel.

  Naturally, it is necessary to predict the stress / strain relationship when a load is applied to the steel structure after reinforcement and the limit points regarding the occurrence of sheet peeling. As described above, the inventors considered that the steel material having a cross-sectional area (equivalent cross-sectional area) obtained by converting the cross-sectional area of the reinforcing fiber sheet into a Young's modulus ratio was integrated with the original steel member. They found that it was possible to accurately predict the actual deformation. In this way, how much cross-sectional area (or number) of reinforcing fiber sheets can be bonded to the steel structure to achieve sufficient reinforcement, and the steel structure that receives the load after reinforcement will be affected by the load of the reinforcing fiber sheet. A sufficiently accurate prediction can be made as to whether or not peeling will occur.

Based on the above reinforcing method, for example, the total cross-sectional area of the reinforcing fiber sheet bonded to the steel member (cross-sectional area in a cross section perpendicular to the direction in which the tensile force acts) is
a) The total cross-sectional area exceeds the value obtained by dividing the necessary steel cross-sectional area by reinforcing the steel member by integrating the steel materials by the Young's modulus ratio,
b) Estimated maximum load on steel members when the steel material with the cross-sectional area multiplied by the above Young's modulus ratio is integrated with the total cross-sectional area. It is appropriate to determine that the strain of the steel member when it is acted on does not exceed the separation limit strain of the reinforcing fiber sheet after bonding.

  When the total cross-sectional area of the reinforcing fiber sheet is determined according to this method including a) and b), the desired strength can be imparted to the steel structure by appropriate reinforcement, and the reinforcing fiber sheet peels off during use after reinforcement. Can be avoided. As described above, the elastic deformation behavior of the steel structure after reinforcement can be accurately predicted by assuming that the steel material with the cross-sectional area converted from the Young's modulus ratio is integrated with the original steel member. Because it can.

In the reinforcing method of the invention, as the reinforcing fiber sheet to be used, carbon fiber (PAN-based or pitch-based carbon fiber), metal fiber (boron fiber, titanium fiber, steel fiber, etc.), glass fiber (glass fiber fiber) or It is preferable to use a sheet in which organic fibers (aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester, or the like) are singly or mixedly mixed.
This is because these reinforcing fiber sheets have high strength and Young's modulus, and the steel structure is reinforced by being bonded to the surface of the steel member. In addition, when using any reinforced fiber sheet, various things, such as an epoxy resin and an acrylic resin, can be used as an impregnation adhesive.

The reinforcing fiber sheet is preferably bonded by impregnating between the fibers of the sheet with room temperature curable or thermosetting epoxy resin, acrylic resin, vinyl ester resin, MMA resin, unsaturated polyester resin or phenol resin.
Thereby, it is possible to appropriately bond the above-mentioned reinforcing fiber sheet to the surface of the steel member and bond the sheets together.

The steel structure reinforcing structure (reinforced structure) according to the claims is characterized in that a plurality of reinforcing fiber sheets are bonded to the surface of the steel member by the steel structure reinforcing method described above. Is.
According to such a reinforcing structure, the steel structure is stably reinforced because the reinforcing fiber sheet is bonded to the surface of the steel member so as not to easily peel off. It can be said that it is an effective reinforcement because it does not cause a decrease in strength due to the heat effect of the processing of the bolt holes or welding, and does not increase the weight burden.

  Since the reinforcing method and the reinforcing structure described in the claims reinforce the steel structure by adhering a reinforcing fiber sheet to the surface of the steel member, the strength of the steel member due to the processing of bolt holes and the thermal effect of welding In addition to incurring a decrease, it does not increase the weight burden of the steel structure, and has the merit that the construction is simple. In particular, the reinforcing fiber sheet used as a reinforcing material is less likely to be peeled off and has the advantage of being able to completely prevent peeling within an assumed load according to appropriate construction, so that stable and permanent reinforcement can be realized. .

  Embodiments of the invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a main part when a steel member 2 of a steel structure (for example, the steel structure of FIG. 3) is reinforced by adhering a carbon fiber sheet 20 on the surface. FIG. 2 shows the relationship between the load and strain in the steel structure 1 before reinforcement (no reinforcement) and after reinforcement, and the occurrence of separation between the steel member 2 and the carbon fiber sheet 20 when a design load is applied. FIG. FIG. 3 is a side view of the steel structure 1 such as a bridge (FIG. 3 (a)), a detailed view of a portion b (a diagram (b1) showing a reference example for comparison) and the embodiment. (B2)), and a diagram (figure (c)) showing the distribution of horizontal shearing force H acting on the bonding surface in the vicinity of part b in FIG. FIG. 4 shows the relationship between stress and strain when a tensile test is performed on a test piece in which five layers (five pieces) of carbon fiber sheets are bonded to one side of a steel piece as shown in FIGS. It is a diagram (figure (a)). Further, FIG. 5 shows the distribution of strain in the sheet when a tensile test is performed on a test piece in which only one layer (one sheet) of a carbon fiber sheet having a length of 200 mm is bonded to one side of a steel piece similar to FIG. Diagram. FIG. 6 is a diagram showing the distribution of horizontal shearing force on the bonding surface measured by changing the number of layers of carbon fiber sheets to be bonded and the amount of shift of the end portions.

First, FIG. 1 shows a reinforcing method for reinforcing a steel member 2 for repair purposes when the steel member 2 of the steel structure 1 has a defect 3 due to corrosion or the like. Such reinforcement is performed by the following procedure. That is,
1) Rust and paint are removed from the steel member 2 to be reinforced by performing a cleansing operation on the defect 3 and its periphery.
2) Fill the defect 3 with the resin 3a and flatten the surface.

3) Apply resin adhesive to the surface of the steel member 2 to be reinforced. As the adhesive, an epoxy resin, an acrylic resin, or the like is used as a component, and an impregnation adhesive that is sufficiently impregnated between the carbon fibers of the carbon fiber sheet 20 to be stacked later is used.
4) Before the adhesive applied to the surface of the steel member 2 is solidified, the carbon fiber sheet 20 (the first layer sheet) is formed on the adhesive (outside, opposite to the steel member 2 and so on). 20-1). The carbon fiber sheet 20 is a cloth-like thin sheet (having a thickness of about 0.1 mm) entangled with long carbon fibers, such as a carbonized acrylic fiber or a material using coal pitch as a raw material. Therefore, it is selected and used according to the required strength. In general, the tensile strength of steel is 400 to 570 N / mm ² and the Young's modulus is 200 kN / mm ² , while the carbon fiber sheet 20 has a tensile strength of 1900 to 3400 N / mm ² and a Young's modulus of 240 to 650 kN. / mm using ^two about things.
5) A similar impregnating adhesive is further applied on the carbon fiber sheet 20 before the adhesive applied in 3) is solidified. A roller or the like may be applied on the surface of the adhesive so that the adhesive is sufficiently impregnated between the fibers of the carbon fiber sheet 20 and the surface is flattened. Then, the adhesive is solidified. One layer of the CFRP sheet is attached onto the steel member 2 by the carbon fiber sheet 20 of 4) and the adhesive applied in 3) and 5).

6) By repeating the above 3) to 5), the carbon fiber sheets 20-2 to 20-n of the second layer to the nth layer and the adhesive are respectively stacked on the first layer, so that a plurality of layers of CFRP sheets are obtained. Are laminated. However, for each layer such as the carbon fiber sheet 20, the respective end portions 21 (21-1, 21-2,..., 21-n) in the direction in which the tensile force acts are shifted stepwise as illustrated.
7) When the CFRP sheet including the carbon fiber sheet 20 is bonded to the steel member 2 by a predetermined number of layers, the cover sheet 26 is attached to the end portion 21 that overlaps in a stepped manner. For this purpose, an adhesive 25 is applied to the surface of the steel member near the end 21-1 of the first layer and the end 21 (21-1, 21-2, ..., 21-n) of each carbon fiber sheet. Then, the cover sheet 26 is bonded onto the adhesive 25. Although various resin sheets can be used as the cover sheet 26, it is preferable in terms of strength to use a CFRP sheet including a carbon fiber sheet.

  Before and after the reinforcement shown in FIG. 1, the relationship between the load and strain in the steel structure 1 changes as shown in FIG. 2. That is, even if a large strain is generated in accordance with the straight line of the gentle slope shown in the figure before reinforcement (no reinforcement), after the reinforcement, the straight line of the steep slope shown in the figure is caused by the function of the high-rigidity carbon fiber sheet 20. Therefore, even if the same load is applied, the strain is reduced.

  When the carbon fiber sheet 20 is bonded to the steel member 2 in accordance with FIG. 1, the limit of separation between the two is when the strain of the steel member 2 reaches about 500 μm according to the tests of the inventors. (When the concentration of the horizontal shearing force H is lowered by overlapping the ends of the carbon fiber sheets 20 stepwise as in FIGS. 1 and 3 (b2)). Therefore, as shown in FIG. 2, as the strain becomes smaller after reinforcement, it is possible to effectively prevent the carbon fiber sheet 20 from peeling off in the design strength.

  The inventors have obtained the results shown in FIG. 4A as data for predicting the elastic deformation behavior of the steel structure after reinforcement by a tensile test using a steel piece to which a carbon fiber sheet is bonded. As shown in FIGS. 4 (b) and 4 (c), five layers (5 sheets) of carbon fiber sheets (CFRP sheets) are bonded to one side of a steel piece, and the steel piece and the carbon fiber sheet are bonded to each other in the longitudinal center portion. The relationship between stress and strain when a tensile test is performed using a test piece with a strain gauge attached is shown.

In the figure, a gently inclined straight line x indicates the relationship between stress and strain when an unreinforced steel piece to which the carbon fiber sheet is not bonded is pulled, and a steeply inclined straight line y indicates that the carbon fiber sheet is bonded. The same relationship is shown when the reinforced steel slab is pulled. The straight line x in the case of the unreinforced steel slab is calculated and illustrated using the Young's modulus of the steel slab as it is, but the straight line y for the reinforced steel slab bonded with the carbon fiber sheet has the Young's modulus as follows: It is a calculation result when it is determined. That is,
Reinforced steel slab Young's modulus = {(Young's modulus of steel slab x cross-sectional area of steel slab)
+ (Young's modulus of steel slab x cross-sectional area of carbon fiber sheet x Young's modulus ratio)}
/ (Cross section of steel slab + Cross section of carbon fiber sheet)
However,
Young's modulus ratio = Young's modulus of carbon fiber sheet / Young's modulus of steel material. Note that the “cross-sectional area” refers to a cross-sectional area in a cross section orthogonal to the direction in which the tensile force acts.

  According to Fig.4 (a), the peeling limit strain of a carbon fiber sheet is about 500 micrometers, and the steel piece (namely, unreinforced steel piece) after a carbon fiber sheet peels is elastically deformed according to the straight line x. And the following facts become clear. That is, the stress-strain relationship measured for the reinforced steel slab that has not peeled is elastically deformed according to the straight line y obtained by the above calculation. This is because the virtual steel slab having a cross-sectional area obtained by multiplying the cross-sectional area of the carbon fiber sheet by the Young's modulus ratio of the sheet and the steel slab is integrated with the original steel member. This means that the elastic deformation behavior of the steel structure (before peeling) can be predicted.

Therefore, for example, in the steel structure 1 of FIG. 1 or FIG. 3A, the total cross-sectional area of the carbon fiber sheet 20 to be bonded to the steel member 2 in order to compensate for the strength decrease due to corrosion or the like is integrated with the steel material. Therefore, it is preferable that the necessary steel material cross-sectional area for reinforcing the steel member is determined so as to exceed the value obtained by dividing the Young's modulus ratio. That is, when the cross-sectional area of the steel material necessary for reinforcing the steel member 2 by integrating the steel material is As and the Young's modulus ratio is ncf, the total required cross-sectional area Acf of the carbon fiber sheet is
Acf = As / ncf
Sought by.

  However, since the carbon fiber sheet 20 peels from the steel member 2 when the above-described peeling limit strain is exceeded, it is necessary to consider that the strain generated in the steel member 2 integrated with the carbon fiber sheet 20 does not exceed this. . Specifically, when it is considered that the steel member 2 is reinforced by integrating a steel material having a cross-sectional integral obtained by multiplying the total cross-sectional area of the carbon fiber sheet 20 to be bonded by the Young's modulus ratio, the design load (assumed It should be checked that the condition that the strain of the steel member 2 does not exceed the separation limit strain is satisfied even when the maximum load) is applied.

  When the end portion 21 of the sheet 20 is shifted in a stepwise manner and bonded as shown in FIG. 1 or FIG. 3 (b2), the shift amount (a dimension corresponding to the depth of each step in the step) is 25 mm. It is good to be the above. This can be explained as follows based on the test results shown in FIGS.

  First, FIG. 5 shows the results of a tensile test performed on a test piece (see the lower figure) in which one layer of a carbon fiber sheet (CFRP) having a length of 200 mm is bonded to one side of a steel piece. In the test, 20%, 40%, 60%, 80%, and 10% of the tensile load Py of the steel slab was applied to the test piece, and the strain (μ) of each part of the carbon fiber sheet at that time was measured. did. In the figure, the horizontal axis indicates the position on the steel piece (distance mm from the center), and the vertical axis indicates the sheet strain (μ). According to this, it can be seen that the carbon fiber sheet has a small strain in the range from about 25 mm from the end thereof, and therefore, in that range, the carbon fiber sheet is less responsible for the tensile load than the vicinity of the central portion.

FIG. 6 shows another result of the investigation conducted in response to the result of FIG. Here, a single-layer or three-layer carbon fiber sheet was bonded to one side of a steel piece similar to the above in a range of 200 mm in length, and in the case of three layers, three types of shift amounts of the end of the sheet were set. In addition, the steel slab was pulled in each case, and the horizontal shearing force at the bonding surface between the steel slab and the sheet was measured. The shift amount of the sheet in the case of three layers was set to 0 mm, 10 mm, and 25 mm between the respective layers. Each will be offset).
According to the result of FIG. 6, a large horizontal shearing force is generated in the vicinity of the end when the sheet is bonded to three layers with the shift amount set to 0 mm. However, when the shift amount between the layers is set to 25 mm, only one layer is generated. Only a small horizontal shearing force is generated in the vicinity of the end as much as the case of bonding. The horizontal shearing force is alleviated in this way when the shift amount between the layers is about 25 mm or more. However, if the sliding amount is too large, the reinforcing range of the steel member by the reinforcing fiber sheet is narrowed. Therefore, it is preferable that the shift amount between each layer is 25 mm or more and about 300 mm or less.

  For bonding the reinforcing fiber sheet 20 such as a carbon fiber sheet to the steel member 2 of the steel structure 1 shown in FIG. 1 or FIG. 3, the end of the sheet 20 is stepped as shown in FIG. 1 or FIG. The sheets 20 can be stacked as shown in FIG. That is, as shown in FIG. 7A, the sheet 20-2 to be stacked on the outer side (outer side) is made longer than the inner sheet 20-1 to be bonded first to the surface of the steel member 2, and further the sheet 20 to be stacked thereon. -3 is longer than the sheet 20-2. When they are joined as shown in FIG. 7B, the end portion 21-2 of the sheet 20-2 protrudes from the end portion 21-1 of the sheet 20-1, and further, the end portion 21 of the outer sheet 20-3. -3 protrudes, but since the adhesive is used over the entire length of each sheet 20, each protruding end 21 is bonded to the surface of the steel member 2.

  Even when the reinforcing fiber sheet 20 is bonded as shown in FIG. 7, the horizontal shearing force generated in the vicinity of the end portion is dispersed, so that the peeling of the sheet 20 is effectively prevented. Since the end 21 of the inner sheet 20 is covered with the end 21 of the outer sheet 20, even if the cover sheet illustrated in FIG. 1 is omitted, an effect equivalent to that of attaching the cover sheet is provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view illustrating a main part in a case where a steel member 2 of a steel structure 1 is reinforced by adhering a carbon fiber sheet 20 on the surface, illustrating an embodiment of the invention. It is a diagram which shows about generation | occurrence | production of the peeling of the carbon fiber sheet when the relationship between the load and distortion in the steel structure 1 after non-reinforcement and reinforcement and a design load acts. Side view of the steel structure 1 to which the reinforcing material is bonded (FIG. 3 (a)), detailed views of the part b (FIGS. 3 (b1) and 3 (b2)), and part b of FIG. 3 (a) It is a diagram (Drawing 3 (c)) showing distribution of horizontal shearing force H which acts on an adhesion surface near. Fig.4 (a) is a diagram which shows the stress-strain relationship of the said steel piece etc. which were obtained by the tension test of the reinforced steel piece. Moreover, each of FIG.4 (b) and FIG.4 (c) is the side view and top view which show the reinforced steel piece used for the tension test. It is a diagram which shows distribution of the distortion | strain in a sheet | seat when a tensile test is done about the steel piece similar to FIG. It is a diagram which shows distribution of the horizontal shear force in an adhesive surface at the time of changing the number of layers of the carbon fiber sheet to adhere | attach, and the shift amount of an edge part. FIGS. 7A and 7B are cross-sectional views showing a procedure in the case where the reinforcing fiber sheet 20 is bonded in another manner on the surface of the steel member 2 of the steel structure 1. It is the side view and schematic diagram which show the conventional reinforcement form with respect to a steel structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel structure 2 Steel member 3 Defect part 20 (20-1, 20-2, ..., 20-n) Reinforcement fiber sheet 21 (21-1, 21-2, ..., 21-n) End part 26 Cover sheet

Claims (6)

A reinforcing method for reinforcing a steel structure in which a tensile force acts on the surface of a steel member, wherein a plurality of reinforcing fiber sheets are bonded to each other on the surface of the steel member and the tensile force acts on the steel member. The end of the reinforcing fiber sheet in the direction being shifted,
The elastic deformation behavior of the steel structure after reinforcement is predicted as a steel material having a cross-sectional area obtained by multiplying the cross-sectional area of the reinforcing fiber sheet by the Young's modulus ratio of the steel sheet and the steel material integrated with an unreinforced steel member. ,
The total cross-sectional area of the reinforcing fiber sheet bonded to the steel member is
a) The total cross-sectional area exceeds the value obtained by dividing the necessary steel cross-sectional area by reinforcing the steel member by integrating the steel materials by the Young's modulus ratio,
b) When the assumed maximum load is applied to the steel member when the steel material of the cross-sectional area obtained by multiplying the total cross-sectional area by the Young's modulus ratio is integrated, the strain of the steel member is A method for reinforcing a steel structure, characterized in that it is determined so as not to exceed a peeling limit strain . The steel structure according to claim 1, wherein a cover sheet for covering the end portion of the reinforcing fiber sheet is attached by adhering the cover sheet to the surface of the steel member and the end portion of the reinforcing fiber sheet. Reinforcement method. Use a thickness less 0.9mm as the reinforcing fiber sheet, the position of the end of each reinforcing fiber sheet in the direction action of the tensile force, shifting more than 25mm per sheet in the direction of action of the tensile force The method for reinforcing a steel structure according to claim 1 or 2 . The steel according to any one of claims 1 to 3 , wherein the reinforcing fiber sheet is a sheet in which carbon fibers, metal fibers, glass fibers, or organic fibers are singly or mixedly mixed. How to reinforce a structure. The bonding of the reinforcing fiber sheet is performed by impregnating between the fibers of the sheet with room temperature curing type or thermosetting type epoxy resin, acrylic resin, vinyl ester resin, MMA resin, unsaturated polyester resin or phenol resin. The method for reinforcing a steel structure according to any one of claims 1 to 4 . A reinforcing structure for a steel structure, wherein a plurality of reinforcing fiber sheets are bonded to the surface of a steel member by the method for reinforcing a steel structure according to any one of claims 1 to 5 .

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