JP2008008142A - Concrete member reinforcing structure and reinforcing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily reinforce a concrete member with a high degree of flexibility according to the shape and dimensions of an object to be reinforced. <P>SOLUTION: A plurality of through holes 18 are provided around an opening 12 provided in an existing beam 10, and reinforcing fiber strands 16 are inserted through two through holes 18 and wound stretchably across them. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reinforcing structure and a reinforcing method for reinforcing a concrete member such as a concrete beam or wall.

  In renovation of existing buildings, openings may be provided to allow piping to pass through existing beams. In that case, since the strength of the beam is reduced around the opening, some reinforcement is required. In addition, there are cases where openings such as windows are newly provided in existing concrete walls. In this case as well, particularly in the vicinity of the corners of the rectangular openings, horizontal and vertical stresses are combined to produce oblique tensile stress. , Cracking is likely to occur. Therefore, in the case of a concrete wall, it is necessary to reinforce around the opening.

Conventionally, as a reinforcing method around the opening of the existing beam, there is a method of joining a reinforcing plate such as a steel plate or a precast concrete plate around the opening. In addition, as a reinforcing method around the opening of the concrete wall, there is a method in which a carbon fiber sheet is attached to the wall surface, and an end thereof is fixed to the concrete of the wall with an anchor bolt through a steel jig (for example, Patent Document) 1).
Japanese Patent No. 3258869

  When renovating an old building, the dimensions of the actual members are often different from the design drawings, even if the design drawings are already lost or the design drawings remain. For this reason, in the method of reinforcing the periphery of the opening of an existing beam with a steel plate or a precast concrete plate, the shape and dimensions of the reinforcing portion are investigated in advance at the site, and a reinforcing steel plate or A precast concrete board must be manufactured, which takes a long construction period as a whole. In addition, if steel plates or precast concrete plates are manufactured according to the dimensions of the reinforcing part, they can be constructed only at the planned location, and there is a problem that the degree of freedom of construction on site is poor. Also, when reinforcing the corner of the existing wall with a carbon fiber sheet, the fixing at the edge of the sheet tends to be insufficiently fixed, and there is a construction site to ensure that the edge of the sheet can be fixed to the existing wall. Often limited.

  The present invention has been made in view of the above points, and provides a reinforcing structure and a reinforcing method capable of easily reinforcing a concrete member with a high degree of freedom according to the shape and size of the object to be reinforced. For the purpose.

  In order to achieve the above object, the present invention provides a reinforcing structure for reinforcing a concrete member, wherein the concrete member is provided with a plurality of through holes for holding a reinforcing fiber material, and the fiber material is It is characterized by being wound through the plurality of through holes.

  According to the present invention, the reinforcing fibers passed through the plurality of through-holes and constraining the concrete can suppress the occurrence and progress of cracks. Moreover, the freedom degree of reinforcement construction becomes high by arrange | positioning a through-hole in the position according to the shape, dimension, etc. of a reinforcement object. Furthermore, since the reinforcing fibers are lightweight and easy to handle, construction work can be easily performed. In the present invention, the concrete member includes a reinforced concrete member, a steel reinforced concrete member, and the like.

  In the present invention, the concrete member may have an opening, and the through hole may be provided around the opening.

  The concrete member may be a beam, wall, or floor of an existing building.

  ADVANTAGE OF THE INVENTION According to this invention, the reinforcement of the concrete member which has an opening part can be performed simply with a high freedom degree according to the shape and dimension of a reinforcement object.

  FIG. 1 is a front view showing a reinforcing structure for a concrete member according to a first embodiment of the present invention. In the present embodiment, the periphery of the opening 12 provided in the existing concrete beam 10 is reinforced. As shown in FIG. 1, a plurality of through holes 18 are provided around the opening 12 so as to surround the opening 12.

  Two or three or more of these through-holes 18 are used as a set, and the fiber strand 16 is inserted into each set of through-holes 18 (every other through-hole 18 in the example of FIG. 1) once or a plurality of times. It is wound. The fiber strand 16 wound in this way surrounds the opening 12 as a whole. The fiber strand 16 is comprised by the fiber with large tensile strength, such as a carbon fiber and an aramid fiber, for example.

  Preferably, the fiber strand 16 is wound between the through holes 18 while introducing tension. In addition, after the fiber strand 16 is wound, the fiber strand 16 is preferably solidified and integrated with an adhesive such as an epoxy resin.

  According to the above configuration, the fiber strand 16 inserted through the through hole 18 so as to surround the opening 12 restrains the concrete of the existing beam 10. For this reason, even if a crack that extends radially from the opening 12 occurs as shown by a broken line in FIG. 2 during an earthquake, the progress of the crack is suppressed by the restraining effect of the fiber strand 16. Therefore, according to the reinforcing structure of the present embodiment, it is possible to improve the yield strength and deformation performance of the existing beam 10. Further, if the fiber strand 16 is wound while introducing a tension, a compressive force can be applied to the concrete of the existing beam 10, so that the progress of the crack can be more effectively suppressed and the occurrence of the crack itself can be suppressed. It can make it difficult to get up.

  Furthermore, according to the shape of the existing beam 10 to be reinforced and the position, size, and shape of the opening portion 12, the formation position of the through hole 18 may be freely set and the fiber strand 16 may be wound, so that the on-site reinforcement work The degree of freedom increases. Moreover, since the fiber strand 16 is very lightweight and easy to handle, the workability at the time of winding is also favorable, and the existing beam 10 can be reinforced by a simple operation.

  In the above-described embodiment, since cracks are generally generated in a direction extending radially from the opening 12, the fiber strand 16 is wound so as to surround the opening 12 so as to be substantially orthogonal to the direction. However, when it can be assumed that cracks are likely to occur in other directions, the fiber strand 16 may be wound in a direction substantially perpendicular to the direction.

Next, a second embodiment of the present invention will be described.
FIG. 3 is a front view showing a reinforcing structure for a concrete member according to the second embodiment of the present invention. As shown in the figure, in this embodiment, the periphery of the rectangular opening 32 provided in the existing or new concrete wall 30, particularly the vicinity of the corner, is reinforced.

  When the rectangular opening 32 is provided in the concrete wall 30, if the reinforcement is not applied, the vertical axial force and the horizontal shearing force are generated in the vicinity of the corner of the opening 32 due to an earthquake or drying shrinkage of concrete. As shown in FIG. 4, cracks tend to occur in a direction extending obliquely from the corner portion. Therefore, in the present embodiment, as shown in FIG. 3, a plurality of through holes 34 are provided in the vicinity of the corner portion of the opening 32 of the concrete wall 30, and the fiber strand 16 used in the first embodiment is used as the through hole 34. And wound one or more times in a direction substantially perpendicular to the direction in which cracks are likely to occur. At that time, the fiber strand 16 is preferably wound while introducing tension, and the wound fiber strand 16 is solidified with a resin and integrated.

  According to the above configuration, even when a crack is generated near the corner of the opening 32, the fiber strand 16 wound in a direction substantially perpendicular to the crack restrains the concrete, thereby suppressing the progress of the crack. It is done. Further, if the fiber strand 16 is wound while introducing tension, a compressive force can be applied to the concrete of the concrete wall 30, so that the progress of the crack can be more effectively suppressed and the occurrence of the crack itself is less likely to occur. can do.

  Therefore, according to this embodiment, it is possible to prevent water leakage and other adverse effects on the interior and exterior due to cracks at the corners of the opening 32 of the concrete wall 30. Moreover, since the fiber strand 16 should just be wound by setting the position of the through-hole 34 freely according to the position and dimension of the opening part 32 of the concrete wall 30, while improving the freedom degree of construction, the fiber strand 16 However, since it is extremely light, good workability can be obtained.

  In addition, although the said embodiment demonstrated the case where this invention was applied to reinforcement of the concrete member which has an opening part, this invention is not limited to this, It is applied also when reinforcing a concrete member which does not have an opening part. Is possible.

Finally, the reason why the generation and progress of cracks in the existing beam 10 and the concrete wall 30 can be suppressed by winding fiber strands as in the above embodiments will be described dynamically. In general, when an earthquake load is applied, an axial force N and a shearing force Q are applied to the column beam frame as shown in FIG. For this reason, a horizontal stress level τ and a vertical stress level σ ₀ are generated in the concrete member, and these are combined to generate an oblique tensile stress level (diagonal tension). The main stress intensity by the diagonal tension, shear cracks will occur upon reaching a tensile strength sigma _t of the concrete. Similarly, when the concrete shrinks by drying, cracks occur when the principal stress caused by the shrinkage reaches the tensile strength of the concrete. In particular, in the vicinity of the opening, stress is concentrated due to the cross-sectional defect of the concrete, and cracking is likely to occur.

The degree of shear stress τ _c at the time of shear crack generation is generally
It is represented by

Here, as shown in FIG. 6, when the fiber strand 16 is wound in a direction orthogonal to the crack, if the compressive stress by the fiber strand 16 is σ _CF , the stress degree τ _c ′ when the shear crack is generated is
It becomes. From this equation, the degree of stress τ _c ′ at the time of occurrence of shear cracks after reinforcement by the fiber strand 16 becomes larger than when there is no reinforcement (that is, when the compressive stress σ _CF does not act), and cracks are less likely to occur. I understand that.

It is a front view which shows the reinforcement structure of the concrete member which is the 1st Embodiment of this invention. It is a figure which shows a mode that a crack arises around the opening part of the existing beam. It is a front view which shows the reinforcement structure of the concrete member which is the 2nd Embodiment of this invention. It is a figure which shows a mode that a crack arises in the corner part vicinity of the rectangular opening part of a concrete wall. It is a figure for demonstrating generation | occurrence | production of the shear crack by an earthquake load. It is a figure for demonstrating the inhibitory effect of the crack generation and progress by a fiber strand.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Existing beam 12 Opening part 16 Fiber strand 18 Through-hole 20 Steel plate 30 Concrete wall 32 Opening part 34 Through-hole

Claims (4)

  A reinforcing structure for reinforcing a concrete member, wherein the concrete member is provided with a plurality of through holes for holding a reinforcing fiber material, and the fiber material is wound through the plurality of through holes. A reinforcing structure characterized by having   The reinforcing structure for a concrete member according to claim 1, wherein the concrete member has an opening, and the through hole is provided around the opening.   The reinforcing structure for a concrete member according to claim 1 or 2, wherein the concrete member is a beam, wall, or floor of an existing building.   A reinforcing method for reinforcing a concrete member, wherein the concrete member is provided with a plurality of through holes for holding a reinforcing fiber material, and the fiber material is wound through the plurality of through holes. Reinforcing method.