JP2006161463A - Reinforcing method of steel member within steel structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforcing method of a steel member within a steel structure which enables effective reinforcement of the steel member within the steel structure, especially the steel member on which a compression force is exerted, and which enables realization of the addition of earthquake-resistant reinforcement by providing durability and toughness against buckling to the steel within an existing steel structure or a newly built steel structure. <P>SOLUTION: The reinforcing method of the steel member within the steel structure is that reinforcement is performed by sticking an FRP plate for reinforcement to the surface of the steel within the steel structure on which the compression force is exerted with an adhesive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for reinforcing a steel material in a steel structure that can be effectively used as a method for reinforcing a steel material that is present in various steel structures and is subjected to compressive force.

  Conventionally, as a reinforcement for steel materials in a steel structure, for example, with regard to seismic reinforcement, a general method is to reinforce a steel member having a certain thickness by welding to a steel member that needs reinforcement. Met.

  However, although welding is a common construction method, there is a disadvantage that it is difficult to use for steel structures because sparks are generated during work, and depending on the skill level and skill of the worker, a good reinforcement effect is always obtained. It wasn't even possible.

  On the other hand, there is a reinforcing fiber material as a conventional reinforcing material, and the fiber reinforcing material has been used mainly for reinforcing a tensile material because its tensile strength is significantly higher than that of a steel material.

  In addition, a method has been proposed in which a buckling strength is improved by adhering an attachment made of steel with an epoxy adhesive to the surface of a steel material to which a compressive force is applied in an existing structure, and clamping with an appropriate clamping means ( Patent Document 1).

However, in this method, the reinforcing material to be bonded is a steel material, which means that the steel material is bonded to each other. Therefore, it is necessary to appropriately select the adhesive and treat the bonding surface, and in addition, When the warpage of the joint surface of the steel material to be reinforced and the accessory does not match, there is a problem that the adhesive strength cannot be obtained and the desired reinforcing effect cannot be obtained as expected.
JP-A-6-330643

  The objective of this invention is providing the reinforcement method of the steel materials in the steel structure which makes it possible to perform effective reinforcement with respect to the steel materials in a steel structure, especially the steel materials to which a compressive force is added.

  In particular, in the present invention, focusing on the reinforcement of the steel material in the steel structure, in the construction of the steel structure, a construction method in which the steel material is joined by a welding method is generally used. Reinforcement of structures by welding methods is not always possible in terms of work accuracy and reliability due to various restrictions (work environment / space, restrictions on the use of fire, etc.) on the construction site. In particular, in the series of seismic diagnosis and seismic strengthening of existing steel structures, even if the seismic diagnosis is properly performed, in terms of executing reinforcement measures based on the diagnosis results This is because the reinforcement of steel structures has not been carried out because no effective reinforcement method has been found yet.

  In particular, it has been desired to realize an effective reinforcing method for steel materials to which a compressive force is applied.

  In other words, the steel material to which the compression force is applied, that is, the so-called compression material, is basically the technology that the steel material is used as a tensile material that receives the tensile force. Depending on the part, both the tensile force and the compressive force may be received or the compressive force and the bending moment may be simultaneously received, and the performance of the member may be determined by the resistance to buckling due to the compressive force or torsion. Because there is.

The method for reinforcing a steel material in a steel structure of the present invention that achieves such an object has the following configuration (1).
(1) A method for reinforcing a steel material in a steel structure, wherein a reinforcing FRP plate is attached to a surface of a steel material to which a compressive force is applied in the steel structure by using an adhesive to reinforce the steel material.

Moreover, the method for reinforcing a steel material in the steel structure of the present invention preferably has the following specific configurations (2) to (5).
(2) The reinforcing FRP plate is composed of at least carbon fiber, aramid fiber or glass fiber, the fibers are arranged substantially in one direction, and the plate width is 10 to 100 mm. A method for reinforcing a steel material in a steel structure as described in (1) above,
(3) The method for reinforcing a steel material in a steel structure according to the above (1) or (2), wherein the pasting range is the front surface or / and the back surface of the steel material to be reinforced.
(4) The reinforcing FRP plate is affixed so that the direction of compressive force applied to the steel material to be reinforced and the fiber long axis direction are parallel to each other, (1), (2) or (3) A method for reinforcing steel in a steel structure.
(5) A plurality of reinforcing FRP plates are affixed, and the aforesaid (1), (2), (3) or ( 4) A method for reinforcing steel in the steel structure described.

  According to the method for reinforcing a steel material in a steel structure of the present invention, a steel material in a steel structure that enables effective reinforcement to a steel material in a steel structure, particularly a steel material to which a compressive force is applied. A reinforcing method is provided, which can provide buckling resistance and toughness to a steel material in a steel structure.

  The reinforcement method in the steel structure of the present invention is to be applied to the existing steel structure, and gives a high reinforcement effect to the steel structure that has become weak due to cross-sectional defects due to rust with the passage of time after construction. It is particularly preferable in that

  However, of course, the steel structure to be reinforced is not limited to the existing structure, and it is also preferable that the structure is performed on the structure together with the new construction.

  Hereinafter, the method for reinforcing a steel material in the steel structure of the present invention will be described in more detail.

  The method of the present invention is characterized in that a reinforcing FRP plate is attached to a surface of a steel material to which a compressive force is applied in a steel structure by using an adhesive to reinforce.

  Here, the steel structure refers to a steel structure that has already been constructed, and the steel structure is formed by using a steel material (steel plate, steel pipe, steel material, steel bar, etc.) for the structure. This is a concept that does not include reinforcing bars in reinforced concrete structures, and reinforcing bars and steel frames in steel reinforced concrete structures.

  In the present invention, the FRP used for reinforcement is a fiber reinforced plastic integrated with a reinforcing fiber and a matrix resin. The reinforcing FRP plate is attached to the surface of a steel material using an adhesive. Attached. The reinforcing FRP plate is composed of at least carbon fibers, aramid fibers, or glass fibers, and the fibers are arranged substantially in one direction and have a plate width of 10 to 100 mm. Is preferred. Among them, the reinforcing fiber used for the reinforcing FRP plate is preferably a carbon fiber, an aramid fiber, or a glass fiber because it is a material that has high tensile strength and can be expected to have some compressive strength. It is further preferable that these reinforcing fibers are arranged substantially in one direction because the reinforcing effect by the fibers can be satisfactorily provided.

According to the various findings of the present inventors, the reinforcing fibers used are those used in the reinforcing FRP at a total use amount (per unit area) of 1200 to 9600 g / m ² after completion of reinforcement. preferable. The total amount of fiber used after completion of reinforcement is the type of steel material to be reinforced, the size (length, width, dimensions, etc.), the cross-sectional shape, the characteristics of the location where the steel material is used, and the type of reinforcing fiber.・ Determine according to the properties etc. as appropriate.

The reinforcing FRP plate used for reinforcement preferably has a plate width of about 10 to 100 mm for reasons such as adhesion workability and handling properties. Moreover, since it sticks and uses on the surface of the steel material to which a compressive force is applied, it is practical that the length of this FRP board for a reinforcement is 1-10 m normally. The reinforcing FRP plate preferably has a thickness within a range of about 1.0 to 6 mm. It is preferable to use one reinforcing FRP plate having a weight of 1600 to 9600 g / m ² , and a fiber usage amount of about 1200 to 7200 g / m ² .

Therefore, as described above, in order to set the fiber amount to 1200 to 9600 g / m ^{2 in} the total use amount (against the area) after completion of reinforcement, the total use amount (against area) of the fiber after reinforcement is usually obtained. in such a 1200~9600g / m ^2, which may be as amount of fibers per FRP plate one is reinforced by appropriately stacking use 1200~2400g / m ² about reinforcing FRP plate It is.

In general, the mechanical properties of the fiber or FRP plate are generally as follows. According to the various findings of the present inventors, the tensile strength in the arrangement direction of the reinforcing fibers is 600 N / mm ^{2 to} 2400 N / mm ² and the Young's modulus is 40kN / mm ² ~370kN / mm and so as to be desirable for use in the ^second range. That is, it is possible to use a material having a mechanical characteristic of the above-mentioned range level in that a reinforcing effect capable of resisting an earthquake of the maximum seismic intensity scale is realized by using the fiber or the FRP plate. It is desirable. However, this is of a nature that fluctuates strictly according to the original seismic strength / strength before reinforcement of the reinforced steel structure.

  That is, if a reinforcing FRP plate having a large Young's modulus is attached, the rigidity is improved and the proof stress is improved, but the energy absorption capacity is small and the deformation is small, so that is preferable from this viewpoint. On the other hand, if a reinforcing FRP plate with a small Young's modulus and a large tensile strength is attached, the yield strength is slightly inferior, but the energy absorption capacity is large and it can withstand large deformations. It can be restored to its original form, which is preferable from this viewpoint.

  And the mechanical characteristic of a fiber or FRP board is the point which brings about the reinforcement effect with respect to the steel material which receives the force of both the tensile force and the compressive force, or both the compressive force and the bending moment as a compressive material in a steel structure. It is preferable that the combination is in a range with a good balance, and more preferably, the total use amount and the total number of use of the reinforcing FRP plates are the tensile strength (tensile strength) 4 in the direction in which the reinforcing fibers are arranged. .8 kN / m to 19.2 kN / m and the tensile rigidity is in the range of 312 kN / mm to 2184 kN / mm.

  When affixing a reinforcing FRP plate according to the present invention, when a plurality of sheets are laminated, the total number of sheets may not be the same shape and size, and the number of superimposed sheets is the most where the compressive force or bending moment is applied. It is also effective to stack them in a staircase pattern so as to increase. In such a case, the entire reinforcing FRP plate at the place where the number of superimposed sheets is the largest should be configured and pasted so as to realize the above-mentioned tensile strength (tensile strength) and tensile rigidity. is there.

  The matrix resin used for the reinforcing FRP plate is preferably a resin such as a polyester resin, an epoxy resin, a phenol resin, a polyamide ester resin, or a polyimide resin.

  The values of the tensile strength and Young's modulus of the entire reinforcing FRP plate described above are generally determined by the fiber type and performance. That is, since the fiber with high strength has a small Young's modulus, the yield strength is moderately increased and the deformation (energy absorption) can be increased. On the other hand, fibers with high Young's modulus have low strength and greatly improved yield strength, but their deformation is small and their toughness is poor. Therefore, the type and performance of the fiber to be used can be determined based on these characteristics.

  Further, as an adhesive for bonding the reinforcing FRP plate to the steel material, polyester resin, epoxy resin, phenol resin, acrylic resin, urethane resin, polyimide resin, or the like can be used. This is most preferable in terms of workability. As the adhesive, a liquid, semi-liquid, solid, semi-solid, such as a lump, powder or sheet can be used.

  However, as the adhesive, those conventionally used for bonding such reinforcing FRP plates (for example, reinforcing FRP plates for reinforcing concrete bridge piers, etc.) may be used. In addition, what makes the above-mentioned matrix resin itself function as an adhesive is also included in the present invention.

  In the present invention, the steel material to which the compression force to be reinforced is applied is a flat steel, a Z-shaped steel, an angle steel, a grooved steel, an H-shaped steel, an I-shaped steel, a steel pipe, or a long structural material of an assembly thereof. This is preferable for obtaining the advantageous effects of the present invention.

  In particular, flat steel, angle steel, groove steel, and the like can be said to be relatively weak in compressive force, and are therefore optimal as objects to be reinforced by the method of the present invention.

  When the reinforcing FRP plate is attached to the steel material to be reinforced, the reinforcing FRP plate is attached so that the direction of the compressive force applied to the steel material and the fiber major axis direction are substantially parallel to each other, thereby obtaining a high reinforcing effect. Most preferred above. When affixing the reinforcing FRP plate, not only one of the plates may be affixed, but also a plurality of layers may be appropriately affixed and a higher reinforcing effect can be obtained. .

  The part to be attached is not particularly limited, but it is preferably attached to a part considered to have a possibility of buckling due to the application of compressive force. For example, as shown in FIG. / And affixed to the part of the steel material to be reinforced having a flat portion with a certain length using the fiber length direction parallel to the direction of the compressive force with respect to the back surface. Is preferred. When it is possible to affix not only the front surface and the back surface but also the side surface, it may be affixed to the side surface.

  FIG. 1 is a schematic perspective model diagram showing an embodiment of a method for reinforcing a steel material in a steel structure according to the present invention as a model.

  In FIG. 1, 1 is a steel structure to be reinforced, 2 is a reinforcing FRP plate, 3 is a steel brace, 4 is a steel column, 5 is a steel beam, 6 is a floor, and 7 is a gusset plate. Shows the case where the reinforcing FRP plate is attached to the two steel braces 3, but the case where the reinforcing FRP plate is attached to the four steel columns is also according to the reinforcing method of the present invention. Yes, it is preferable.

  When using a plurality of reinforcing FRP plates and affixing the reinforcing FRP plates to a plurality of surfaces, respectively, the reinforcing FRP plates may be attached so that the plate surface directions thereof are parallel, You may make it stick so that each board surface direction may be below the direction which cross | intersects. This is because it is possible to cope with a case where the direction in which the compressive force is applied cannot be predicted as a specific direction, or to cope with an eccentric force.

  In addition, after attaching the reinforcing FRP plate to the surface of the steel material to be reinforced according to the method of the present invention using an adhesive, the fiber bundle or the fiber sheet is further covered so as to cover the reinforcing FRP plate. Alternatively, a fiber bundle or a fiber sheet impregnated with a resin may be wound to further improve the appearance and the reinforcing effect.

  Hereinafter, based on an Example, the concrete structure and effect of the reinforcement method of the steel materials in the steel structure of this invention are demonstrated.

  In addition, Examples 1-5 and the comparative example 1 are the Examples and comparative examples regarding the case where this invention method is employ | adopted as reinforcement of the steel material which a compression force applies.

Example 6 and Comparative Example 2 are an example and a comparative example relating to the case where the method of the present invention is employed as reinforcement of a steel material to which a compressive force and a bending moment are simultaneously applied.
Example 1
Among various reinforcing FRP plates marketed for reinforcement of reinforced concrete, the tensile strength, which is classified as the high strength type, is 2400 kN / mm ² , Young's modulus is 156 kN / mm ² , length is 1280 mm, width Prepared 4 sheets of reinforcing FRP plates (reinforcing fiber: carbon fiber, matrix resin: epoxy resin) having a thickness of 50 mm and a thickness of 2 mm.

  These reinforcing FRP plates are made of angle steel (L-shaped steel, length 1300 mm, length of one side of the L-shaped section: 50 mm, length of the other side of the L-shaped section: 50 mm, Adhesion using epoxy resin as an adhesive to a total of four surfaces, the inner and outer surfaces of each of the two surfaces forming the L shape, under the direction of the intersecting plate surfaces of the same thickness: 4 mm) It was. The pasting was performed so that the fiber length direction in the FRP plate was parallel to the length direction of the angle steel. FIG. 2 is an external perspective model view after the affixing, 8 is a steel structure as an object to be reinforced, and 2 is a reinforcing FRP plate.

  A compressive force was applied from both ends to the angle steel with the reinforcing FRP plate attached thereto, and the durability against the compressive force was judged from the measurement results of various physical properties.

  When applying the compressive force from both ends, a square steel plate 9 (200 mm × 180 mm) is fixed to both ends of the angle steel 8 using pins as shown in the model diagram of FIG. A compression load was slowly and statically applied to the angle steel using a jack.

  The compression test was performed until the angle steel buckled, the attached reinforcing FRP plate was peeled off, or the attached reinforcing FRP plate was broken in the layer. (If any event occurs, compression ends at that point.)

  The evaluation data includes the maximum load, the displacement at the maximum load (displacement in the central part in the length direction of the angle steel (central displacement)), and the maximum central displacement between the start of compression and the end of compression. The amount of residual displacement and the amount of displacement at the time of failure were measured.

The results are shown in Table 1.
Example 2
Medium elastic type and classification has been has tensile strength 1500kN / mm ² in the various reinforcing FRP plate which is commercially available for concrete construction, Young's Modulus is a 273kN / mm ^2, length 1280 mm, width Except that four reinforcing FRP plates (reinforcing fiber: carbon fiber, matrix resin: epoxy resin) having a thickness of 50 mm and a thickness of 2 mm were prepared and used, all were the same as in Example 1 under the same conditions as in Example 1. It used for the compressive force provision test.

The results are as shown in Table 1.
Example 3
The same FRP plate as that used in Example 1 is the same FRP plate, except that four types of reinforcing FRP plates, each of which has a different size, are prepared. 1: Length 1280 mm, width 50 mm, thickness 2 mm, 2: length 640 mm, width 50 mm, thickness 2 mm, part 3: length 450 mm, width 50 mm, thickness 2 mm, part 4: length 210 mm, width 50 mm, thickness 2 mm), and the same angle-shaped steel material as in Example 1 was attached to the center in the length direction and to the two outer surfaces in order from the larger dimension in order. Others were subjected to the same compressive force application test as described in Example 1 under the same conditions as in Example 1.

  FIG. 4 is an external perspective model view after being attached, 8 is a steel structure as an object to be reinforced, and 2 is a reinforcing FRP plate.

The results are as shown in Table 1.
Example 4
Instead of the reinforcing FRP plate used in the third embodiment, the same FRP plate as that used in the second embodiment and the same specification is used, but only the dimensions are the same as those in the third embodiment. 8 reinforcing FRP plates prepared (Part 1: Length 1280 mm, Width 50 mm, Thickness 2 mm, Part 2: Length 640 mm, Width 50 mm, Thickness 2 mm, Part 3: Length 450 mm, width 50 mm, thickness 2 mm, 4: length 210 mm, width 50 mm, thickness 2 mm), etc. All other conditions were the same as in Example 3 and subjected to a compressive force application test.

The results are as shown in Table 1.
Example 5
Prepare four FRP plates for reinforcement similar to those used in Example 1, and affix a total of four sheets (two on each side) to the outer surfaces of the two surfaces forming the L-shape. Except for the above, all were subjected to the same compressive force application test as in Example 1 under the same conditions as in Example 1.

The results are as shown in Table 1.
Comparative Example 1
Except not using any reinforcing FRP plate, all were subjected to the same compression force application test as in Example 1 under the same conditions as in Example 1.

  The results are as shown in Table 1.

  In each evaluation parameter, the maximum load (kN) is the maximum load applied to the angle steel from the start of load application to the release of the application of the load (compression force). It can be said that the angle steel material was able to withstand this maximum load value, but after showing the maximum load, the load itself became small with further deformation and buckling, and plastic deformation progressed further. (In some cases, it can lead to immediate destruction.)

  It can be said that a higher maximum load is better. Further, the displacement (mm) at the maximum load is a displacement amount when the maximum load is applied, and is a value indicating how much the center portion of the steel material is deviated from before the compression force is applied. This value means that the smaller the steel load itself, the smaller the deformation even when the maximum load is applied.

  According to the present invention, the maximum load value is about 2-3 times larger than that of Comparative Example 1, and even when the maximum load is applied, the displacement is small, and the load resistance and durability are very high. It can be seen that the performance is improved.

  On the other hand, the maximum central displacement is the maximum value of displacement at the central portion of the angle steel between the start of load application and the release of application of load (compression force).

  As can be seen from Table 1, in Examples 1 to 5 according to the present invention, the maximum load value is about 2 to 3 times larger than that in Comparative Example 1, and when the maximum load is applied. However, it can be seen that the displacement at the central part of the steel material is as small as about 1/3 to 3/4, and the displacement is less than that of Comparative Example 1 and the load resistance and durability are greatly improved.

  On the other hand, the maximum central displacement of Comparative Example 1 shows a high value (80 mm), but the residual deformation value is also high (75.5 mm), and in the case of Comparative Example 1, the plastic deformation no longer exceeds the elastic limit. It can be seen that the region is deformed. On the other hand, according to the present invention, the maximum central displacement is smaller than that of Comparative Example 1, and the residual deformation is also smaller.

  As described above, according to the method of the present invention, even when subjected to a compressive force, the displacement is smaller than that of a blank product that does not perform any reinforcement, and the displacement can be determined to be in a more elastic deformation region. It can be said that the load resistance, durability and toughness against the compressive force are large. That is, it is difficult to buckle, deform or break due to compressive force, and even if it is deformed, the power to restore the original shape when the load is released is significantly higher than that of the blank product (Comparative Example 1). It is big and good.

As can be seen from Examples 1 to 5, even in the case of the method of the present invention, depending on the usage method / structure, etc. of the reinforcing FRP plate (arrangement and attaching method of reinforcing fibers, usage amount, etc.) Multiple properties such as strength, load resistance / durability and toughness can be configured to emphasize one of the properties over the other, and these correspond to the characteristics of the reinforced steel structure as appropriate. It is possible to use them properly.
Example 6
Two reinforcing FRP plates identical to those used in Example 1 were attached to the outer sides of both flanges of the H-shaped steel forming an H-shaped steel column having a length of 2000 mm using epoxy resin.

  As shown in FIGS. 5A and 5B, the details of the H-shaped steel are as follows: steel length 2000 mm, H-shaped height 100 mm, H-shaped width 100 mm, web portion thickness 6 mm, flange portion thickness 8 mm.

  First, a constant compressive force was applied to the columnar member made of H-shaped steel to which the reinforcing FRP plate was attached with a manual jack. Specifically, while maintaining the axial force (compression force) at 200 kN, a bending moment about the strong axis (X axis) was loaded on the lower end of the H-shaped steel via an arm by an actuator.

The maximum bending moment and the displacement at the maximum bending moment were measured, and the results are shown in Table 2.
Comparative Example 2
Except for not using the reinforcing FRP plate, the same conditions as in Example 6 were applied, and the bending moment was applied to the lower end of the H-shaped steel while maintaining the axial force (compression force) at 200 kN as in Example 6. Was loaded through the arm.

  The maximum bending moment and the displacement at the maximum bending moment were measured, and the results are shown in Table 2.

  As shown in Table 2, in the comparative tests of Example 6 and Comparative Example 2, the moment at which the specimens cause lateral buckling is 8046 kN in the case of no reinforcement (Comparative Example 2), and the reinforced specimens according to the present invention. In (Example 6), it became 106332 kN, and the improvement effect of about 32% was recognized.

  If the bending moment is increased around the strong axis (X axis) at the end while maintaining the axial force at 200 kN, rotation occurs around the weak axis from a certain moment, and the buckling strength decreases rapidly. By attaching the reinforcing FRP plate according to the present invention, the transition to the rotation around the weak axis could be delayed.

FIG. 1 is a schematic perspective model diagram showing an embodiment of a method for reinforcing a steel material in a steel structure according to the present invention as a model. FIG. 2 is a view for explaining a method of sticking a reinforcing FRP plate used for evaluation in Example 1 of a method for reinforcing a steel material in a steel structure of the present invention. It is an external appearance perspective model figure after affixing. FIG. 3 is a diagram for explaining a compression test method employed for evaluating each method of reinforcing a steel material in a steel structure according to the present invention. FIG. 4 is a view for explaining the test methods employed in Examples 3 and 4 of the method for reinforcing a steel material in a steel structure according to the present invention, and is an external perspective view after a reinforcing FRP plate is attached. It is a model figure. 5 (a) and 5 (b) are model diagrams showing an outline of a columnar material made of H-shaped steel used in Example 6, and (a) is a schematic cross-sectional view showing an H-shaped cross-sectional structure; b) is a schematic front view.

Explanation of symbols

1: Steel structure as an object to be reinforced 2: FRP plate for reinforcement 3: Steel brace 4: Steel pillar 5: Steel beam 6: Floor 7: Gusset plate 8: Angle steel 9: Square steel plate

Claims (5)

  A method for reinforcing a steel material in a steel structure, characterized by attaching a reinforcing FRP plate to a surface of a steel material to which a compressive force or a compressive force and a bending moment in the steel structure are simultaneously applied by using an adhesive. .   The reinforcing FRP plate is composed of at least carbon fiber, aramid fiber or glass fiber, the fibers are arranged substantially in one direction, and the plate width is 10 to 100 mm. A method for reinforcing a steel material in a steel structure according to claim 1.   The method for reinforcing a steel material in a steel structure according to claim 1 or 2, wherein the pasting range is a front surface and / or a back surface of the steel material to be reinforced.   4. The reinforcement of a steel material in a steel structure according to claim 1, wherein the reinforcing FRP plate is attached so that the direction of compressive force applied to the steel material to be reinforced is parallel to the fiber major axis direction. Method.   5. A steel material in a steel structure according to claim 1, wherein a plurality of reinforcing FRP plates are pasted and are pasted in a direction in which the plate surface directions intersect each other. Reinforcement method.

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