JP2005105684A - Leaf spring-shaped fiber-reinforced resin plate, and structure reinforcing method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon fiber plate which accomplishes a high reinforcing effect without complication of operations. <P>SOLUTION: This carbon fiber plate is an FRP plate which can be obtained in such a manner that fibers are impregnated/cured with a resin, and an inside part with respect to either of longitudinal ends of the FRP plate is thickly molded. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to reinforcement of a structure using a fiber reinforced resin plate, and more particularly to a fiber reinforced resin plate having a shape adapted to a reinforcement application and a structure reinforcement method using the same.

  In general, the structure is made of metal such as iron, wood, concrete, and the like, and the strength varies greatly depending on the design standards at the time of construction, as well as the decrease in yield strength due to aging. Also, in the previous Great Hanshin-Awaji Earthquake, the existing seismic standards were reviewed based on the experience that damage to buildings that met the standards of the new seismic design method enforced in 1981 was minor. Goods are also required to comply with the new seismic standards.

  In the case of an existing building, if it is demolished and newly constructed, a building that satisfies the new earthquake resistance standard can be obtained. However, it takes a long time to build, and the cost is great. Therefore, normally, repair and reinforcement work is carried out unless the deterioration is significant.

  In addition to seismic reinforcement, there is an urgent need to reinforce road floor slabs and girders in response to the relaxation of loading regulations. Furthermore, there is a growing interest in measures to prevent concrete from coming off tunnels, overpasses, and bridges.

  There is also a method to reinforce using steel materials for repair and reinforcement work, but because the weight of the material itself is heavy, it is necessary to use heavy machinery for construction, and it also increases the weight of the structure itself, which is preferable. Absent. Furthermore, there is a problem that the reinforcing material itself is easily deteriorated by rust or the like.

  Therefore, recently, restoration and reinforcement using reinforcing fibers have been attracting attention as materials that can replace such steel materials. In particular, carbon fiber as a reinforcing fiber has properties of about 10 times the strength and about 1/5 the strength of steel materials, and is lightweight while being strong and yet does not corrode. For this reason, there is an advantage that heavy machinery is not required for construction, construction work can be easily performed in a short time, and the weight of the structure to be repaired or reinforced does not increase greatly.

  However, carbon fiber is not versatile and has excellent tensile stress in the fiber length direction, but has low compressive stress. It can be used for repair and reinforcement work such as bending reinforcement and shear reinforcement utilizing these characteristics. Applied.

  In repair / reinforcement work using reinforced fiber, first, after correcting the unevenness of the part to be reinforced, a primer layer is formed if necessary, and a reinforced fiber sheet or reinforced fiber prepreg sheet is attached, and thermosetting The resin is impregnated or the thermosetting resin impregnated in advance is heated and cured to convert the repair / reinforcing surface into a fiber reinforced resin (FRP) plate and to fix it to the surface. In addition, for the purpose of omitting the heat curing step, a method of attaching a pre-cured FRP plate is also known.

  Since the stress applied to the structure is different, when using a pre-cured FRP plate, prepare an FRP plate with a different thickness, or use an FRP plate with reinforcing fibers of different strength, which is suitable for the stress. The existing FRP plate is laminated and used in a part where a large stress is applied.

  However, the applied stress is not uniform even at the application site. For example, in the case of a structural beam or the like, a greater stress is applied to the central portion. In such a case, since it is used by being laminated so as to correspond to the largest stress, a portion having a small stress is wasted.

  On the other hand, Patent Document 1 (Japanese Patent Laid-Open No. 9-67941) discloses a structure in which FRP plates are overlapped and reinforced in order of leaf springs so that the number of stacked layers increases in the central portion where stress is applied most. A structure for pasting is shown. That is, as shown in FIG. 3, when reinforcing the beam 10 between the columns 20, the base plate 1 is first attached, and the laminated plates 2A, 2B, and 2C are sequentially attached thereon to form a leaf spring. According to this method, the number of FRP plates to be laminated can be optimally selected according to the stress state, and the cost increase can be suppressed despite a sufficiently high reinforcing effect.

  However, in this method, it is necessary to bond and superimpose FRP plates that are sequentially shortened at the work site, and they have to be aligned and bonded together, resulting in a complicated operation. Moreover, although it is necessary to arrange | position a several FRP board in parallel for reinforcement of large areas, such as a floor slab, the same process will be given to each. In addition, the work site is often dusty and foreign substances are likely to be mixed into the adhesive. Further, the curing characteristics of the adhesive itself are easily changed depending on the temperature and humidity.

Furthermore, in the case of steel structures, the rate of elongation is greater than that of concrete, and it is necessary to increase the number of layers to suppress this elongation. Curing takes a long time and is not practical.
JP-A-9-67941

  An object of the present invention is to achieve a high reinforcing effect without complicating work.

  In the present invention, instead of laminating a plurality of FRP sheets, the use of FRP sheets having different thicknesses at both ends and the center of one FRP sheet eliminates the need for on-site bonding work. In addition, the reinforcement corresponding to the stress can be performed accurately.

  That is, the present invention relates to a fiber reinforced resin plate obtained by impregnating and curing a resin in a fiber, and a leaf spring in which the inner part is formed thicker than any one end in the longitudinal direction of the fiber reinforced resin plate It is a fiber-reinforced resin plate.

  The present invention also provides a method for reinforcing a structure by attaching a fiber reinforced resin plate obtained by impregnating and curing a resin to a structure to be reinforced. The present invention relates to a method for reinforcing a structure, characterized in that a leaf spring-like fiber reinforced resin plate is used and the stress center of the leaf spring-like fiber reinforced resin plate is aligned and bonded to a portion where the maximum stress of the reinforcement portion is applied.

  In the present invention, since a fiber reinforced resin plate (FRP plate) that is integrally formed in the shape of a leaf spring is used in advance, the bonding work at the work site is unnecessary, the work time can be greatly shortened, and the adhesion is 1 It is less affected by the on-site environment because it only takes one time. In addition, since the FRP plate molded in advance in advance is easy to confirm the rigidity and confirm the stress center, it is easier to perform the bonding operation by marking the center of the FRP plate.

  By forming it integrally in the factory, it is possible to manufacture leaf spring-shaped reinforcing members with stable quality, making quality control easy, and compared to on-site bonding work, there are variations in temperature, humidity, and working personnel. Less.

  The FRP plate used in the present invention is obtained by impregnating and curing a thermosetting resin in a fiber.

The reinforcing fiber to be used is not particularly limited, and carbon fiber, glass fiber, aramid fiber, other organic fiber, and the like can be used, and can be appropriately selected according to the application. Among them, carbon fiber is preferable. For example, in the tensile test method of carbon fiber reinforced plastic in accordance with JIS K7073, the standard product (S type) is 1.52 × 10 ⁵ N / mm ² or more, and the medium elastic product (M type). ) Use a material having a tensile elastic modulus of 1.96 × 10 ⁵ N / mm ² or more, and a highly elastic product (H type) has a tensile elastic modulus of 2.94 × 10 ⁵ N / mm ² or more.

  In particular, as an FRP plate, a prepreg sheet obtained by impregnating a fiber aligned in one direction with a resin is laminated in the same direction so that a desired reinforcing strength can be obtained. What is obtained by heating and curing the resin is preferable, and the leaf spring-like FRP plate of the present invention is obtained by laminating prepreg sheets having different lengths sequentially to obtain a laminate, and curing the resin by pressing and heating. Is obtained.

  First, the longest prepreg sheet is used for a portion (base portion) to be a bonding surface with the structure, and a prepreg sheet shorter than the base portion is laminated thereon. At this time, the prepreg sheets to be laminated on the base portion may be laminated so that the lengths are sequentially shortened, or conversely, may be laminated so as to be sequentially long from the shortest, and further, the prepreg sheets are laminated in any order. Also good. This is because these are finally cured by pressurization and heating, so that even if the layers are stacked in any order, the thickness corresponding to the number of layers in the portion can be obtained. Moreover, depending on the case, a part of prepreg sheet laminated | stacked on a base part can also be made into the same length as a base part. In this way, a leaf spring-like integrally formed FRP plate as shown in the schematic perspective view of FIG. 1 is obtained.

  Further, as shown in FIG. 2A, the leaf spring-like FRP plate of the present invention is preferably manufactured symmetrically with respect to the center A in the longitudinal direction. In this case, the stress center B of the FRP plate The center in the longitudinal direction (the center with the pasting surface) matches. However, depending on the upper structure of the reinforcing part, the stress may not be maximized at the center of the attaching part. In order to cope with this, as shown in FIG. 2B, the stress center B 'can be manufactured so as to be shifted from the longitudinal center A' of the FRP plate. In this case, both ends of the FRP plate need not have the same thickness.

  In the present invention, the difference in thickness means that the thickness of one or more prepreg sheets is different, but it goes without saying that the thickness is optimum for the stress state of the structure.

  Next, a method for reinforcing a structure using the leaf spring-like FRP plate of the present invention will be described.

  In the reinforcement of a structure using the leaf spring-like FRP plate of the present invention, the effect is exhibited particularly in a portion where a large bending stress is applied particularly in a beam or a floor slab of the structure. Among them, it is particularly effective for reinforcing steel structures having a high elongation rate.

  In the construction, the ground treatment of the place to be reinforced is performed. For example, when reinforcing existing concrete, in the ground treatment, finish the surface of the existing concrete to which the FRP plate is attached, remove fragile concrete, dust, dirt, etc. by removing the area slightly wider than the FRP plate width by blasting or disc sandering. After that, repair the cracks (resin injection), etc., and ensure the soundness of the concrete surface. Also, the unevenness and unevenness caused by the removal of the finishing material should be repaired with polymer cement mortar. When reinforcing a steel material, it is preferable to remove paint or rust.

  When carbon fiber is used as the fiber, the concrete surface may be reinforced so as to be an FRP plate having a maximum thickness of 1 to 2 mm. In the case of a steel structure, the maximum thickness is about 10 to 20 mm. It becomes. For example, in the case of a prepreg sheet having a thickness of 0.5 mm, about 20 to 40 sheets need to be laminated.

  Next, primer coating is performed to improve the adhesion between the structure and the FRP plate. Depending on the adhesive used, this step can be omitted.

  An adhesive is applied to the surface of the structure on which the primer has been applied in this manner. On the other hand, an adhesive is applied to the FRP plate in a trapezoidal shape using a dedicated jig. In order to improve adhesiveness, it is desirable to roughen the adhesive surface of the plate with sandpaper, a grinder or the like. Press with a roller or the like so that no gap remains between the structure and the FRP plate. At this time, the adhesive is pressed until it is pushed out from both sides of the FRP plate, and the protruding adhesive is removed before curing. Moreover, it is desirable to remove the adhesive if it also adheres to the surface of the FRP plate.

  Here, the adhesive to be used is not particularly limited as long as it is an adhesive that can sufficiently bond the FRP plate and the structure to be reinforced and can maintain a desired reinforcing effect. Epoxy adhesives can be used. The amount of the adhesive used varies depending on the state of the base, etc., but is usually about 0.3 to 0.5 kg / m for a 50 mm wide FRP plate.

  In the present invention, the highest stress portion (stress center) of the FRP plate of the present invention is aligned and pasted to the most stressed portion of the structure. At this time, positioning can be easily performed by marking the stress center of the FRP plate.

  In addition, in existing concrete, peeling by the base material destruction of the end part may occur only by pasting together. In such a case, a conventionally known peeling preventing means may be provided for the end part. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

Example 1
A similar prepreg sheet in which two carbon fiber prepreg sheets each having a thickness of 0.5 mm, a width of 100 mm, and a length of 2000 mm aligned in one direction are stacked on the base portion, and the length is successively shortened by 100 mm. A total of 9 pairs were stacked with the center in the longitudinal direction aligned two by two, and these were pressure-pressed from above and heat cured to produce a leaf spring-like carbon fiber reinforced (CCF) plate. The end of this CCF plate was 1 mm thick, and the center was 10 mm thick.

  After the bottom surface of the steel bridge to be reinforced is ground-treated, a primer layer is applied and formed on the plate spring-like CCF plate attachment surface, and an adhesive (trade name “Bond E-2370M” manufactured by Konishi Co., Ltd.) is predetermined. The adhesive was applied in the same manner after the thickness was applied and the adhesive surface of the CCF plate was roughened. The center of the CCF plate was attached in alignment with the center of the beam, and was sufficiently pressed using a roller so that no gap was generated between the beam and the CCF plate, and the protruding adhesive was removed.

Comparative Example From a long unidirectional reinforced carbon fiber plate having a width of 100 mm and a thickness of 2 mm, 10 plates each having a length of 100 mm each having a length of 100 mm were cut out from 2000 mm to 1000 mm. It was bonded to the lower surface of the steel bridge, and was further reinforced by sequentially bonding the longer to shorter ones. If the next plate is pasted before the adhesive is sufficiently cured, the plate may be displaced, and it is necessary to bond the adhesive after the adhesive is cured to some extent. It took several days to cure the adhesive.

It is a schematic perspective view which shows an example of the leaf | plate spring-like FRP plate of this invention. It is sectional drawing of the leaf | plate spring-like FRP plate of this invention, (a) is a FRP plate manufactured by laminating | stacking symmetrically about the center of a longitudinal direction, (b) has a stress center in the position shifted | deviated from the center of a longitudinal direction. FRP plate. It is sectional drawing which shows the reinforcement method of the beam part which becomes a prior art example.

Claims (4)

  A fiber reinforced resin plate obtained by impregnating and curing a resin with a fiber, and a plate spring-like fiber reinforced resin plate having a thicker inner portion than either one end in the longitudinal direction of the fiber reinforced resin plate .   The leaf-spring-like fiber-reinforced resin plate according to claim 1, wherein the plate-spring-like fiber-reinforced resin plate is formed so as to increase in thickness from both ends toward the longitudinal center.   The leaf spring-like fiber reinforced resin plate according to claim 1 or 2, wherein a mark is applied to a central portion of the stress.   In the reinforcing method of a structure by sticking a fiber reinforced resin plate obtained by impregnating and curing a resin to a fiber to a structure to be reinforced, as the fiber reinforced resin plate, any one of claims 1 to 3 A structure reinforcement comprising the leaf spring-like fiber reinforced resin plate according to claim 1, wherein the stress center of the leaf spring-like fiber reinforced resin plate is aligned and bonded to a portion where the maximum stress is applied to the reinforcement portion. Method.

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