JP2006132081A - Footing reinforcing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reinforce a continuous footing of plain concrete against differential settlement and an earthquake. <P>SOLUTION: In this footing reinforcing structure 1, aramid fiber sheets 4a and 4b as fiber sheets are bonded to both side surfaces 3a and 3b of the continuous footing 2, composed of the plain concrete, in a desired horizontal length range from a raised section of the continuous footing to an upper surface thereof. Preferably, the horizontal length of the adhesion of the sheets 4a and 4b is set to be the overall length of the continuous footing. Since a projected corner and an internal corner ordinarily exist in the continuous footing, in this case, the aramid fiber sheets are bonded in an appropriately split manner, or continuously bonded while the corner, particularly, the internal corner is held by a holding member such as a metal fitting. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention mainly relates to a foundation reinforcing structure for reinforcing a cloth foundation of a house.

  Recent housing foundations are often constructed as reinforced concrete (RC) structure fabric foundations that stand on the bottom plate that is a footing and have an inverted T-shaped cross-section along with the footing. In most cases, the structure has a predetermined strength. However, for old houses, specifically for houses before 1986, when the law stipulates that construction should be done as an RC foundation, unreinforced concrete. There are many fabric foundations.

  Therefore, it is desirable to take some reinforcement measures for such an unreinforced concrete cloth foundation. Specifically, the existing unreinforced concrete cloth foundation is often reinforced by RC reinforcement.

JP 11-131494 A Tomi-3095525 Tomi-3087712

  However, there is a problem that RC reinforcement is not practical in terms of construction period or cost, and in the known method, the in-plane bending moment caused by an earthquake or non-uniform settlement is applied to the cloth foundation of an existing building. There has been a problem that the reinforcement sufficient to resist cannot be performed sufficiently and efficiently.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a foundation reinforcing structure capable of reinforcing an unreinforced concrete cloth foundation against uneven settlement and earthquake.

  In order to achieve the above object, the foundation reinforcing structure according to the present invention has a desired horizontal length from the rising portion to the top edge of the fabric foundation on both sides of the fabric foundation made of unreinforced concrete. By bonding the fiber sheet in the range, it is configured to suppress cracks due to in-plane bending moments generated in the fabric foundation and cracks due to out-of-plane bending.

  In addition, the foundation reinforcing structure according to the present invention includes a pair of fiber sheets that are bonded in two upper and lower stages in the vicinity of the rising portion and near the top end of the outdoor side surface of the cloth foundation made of unreinforced concrete, and the pair of fibers. The fiber sheet is bonded to the indoor side surface so that the intermediate height of the sheet and the height above the ground surface is the bonding position.

  In the basic reinforcing structure according to the present invention, the fiber sheet is an aramid fiber sheet.

  Cracks (cracks) in unreinforced concrete are due to the fact that the tensile strength of the concrete is small, but the applicant is basically concerned about the reason why tensile stress is generated in the fabric foundation made of unreinforced concrete. We went back and examined it by comparing it with the underground beams found in medium-sized and larger buildings.

  Here, the underground beam in the RC structure is configured as a beam, as the name suggests, and the reinforcement is arranged so that it can resist in-plane bending moments (bending moments around the horizontal axis) due to uneven settlement or earthquakes. Although the amount and bar arrangement are set, for unreinforced concrete foundations, there are no reinforcing bars, so when an in-plane bending moment acts on the fabric foundation, cracks will occur at the tension side. .

  The in-plane bending moment is mainly caused by the unsettled settlement due to insufficient earth bearing capacity or the pulling force acting on the column during an earthquake, resulting in forced deformation or external force acting on the fabric foundation, which causes tensile stress in the fabric foundation. It was found that cracking occurred.

  Considering this point, it is sufficient to simply bond the fiber sheet to the side of the cloth foundation of unreinforced concrete.

  However, if the fiber sheet is bonded to only one side of the fabric foundation in a situation where an in-plane bending moment is generated, a large difference in tensile resistance occurs on both sides of the fabric foundation, and the fabric sheet is bonded to the side where the fiber sheet is not bonded. There is a concern that the foundation bends in the out-of-plane direction, and a tensile stress is generated on the convex side to cause cracks.

  Based on this viewpoint, the applicant significantly improves the in-plane bending resistance by adhering the fiber sheet to both sides of the fabric foundation in the desired horizontal length range from the rising edge to the top edge of the fabric foundation. Thus, even in unreinforced concrete, it has been found that the tensile stress generated by uneven settlement and earthquake can be borne by the fiber sheet and cracking of unreinforced concrete can be suppressed. It is a thing.

  In addition, the Applicant must avoid the situation in the renovation work near the rising part of the outdoor side surface and the ceiling so as to avoid the situation where the resident's life is forced to change, such as peeling off the first-floor floorboard or removing a part of the wall. A pair of fiber sheets are bonded in the upper and lower stages in the vicinity of the ends, and the fiber sheet is attached to the indoor side surface so that the intermediate height of the pair of fiber sheets and the height above the ground surface is the bonding position. Adhesion has led to a novel invention that can reduce the work under the first floor and balance the tensile strength between the outdoor side and the indoor side, and can perform the renovation work more efficiently.

  That is, in the foundation reinforcing structure according to the present invention, the fiber sheet is bonded to both sides of the fabric foundation made of unreinforced concrete in a desired horizontal length range from the rising portion to the top edge of the fabric foundation. In the configuration, since the fiber sheet bears the tensile stress generated in unreinforced concrete, it is possible to prevent cracks in unreinforced concrete, especially bending cracks at the base top edge or rising part due to in-plane bending moment. At the same time, since it adheres to both side surfaces of the fabric foundation, there is no concern that the tensile forces are balanced and bent in the out-of-plane direction, that is, either on the outdoor side or on the indoor side to cause cracks on the side surfaces.

  Further, in the foundation reinforcing structure according to the present invention, a pair of fiber sheets are bonded in two steps up and down in the vicinity of the rising portion and near the top end of the outdoor side surface of the cloth foundation made of unreinforced concrete, The fiber sheet is bonded to the indoor side so that the intermediate height of the fiber sheet is equal to or higher than the ground surface, and in this configuration, the same effects as the above-described invention are achieved. In addition to the above, since it is not necessary to excavate the ground when constructing the indoor side, the burden on the worker is reduced and the renovation work can be performed efficiently.

  As the fiber sheet, in addition to an aramid fiber sheet, a fiber sheet having a high tensile strength such as a carbon fiber sheet can be used.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a foundation reinforcing structure according to the present invention will be described with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.

(First embodiment)

  FIG. 1 is a view showing a foundation reinforcing structure according to the present embodiment. As can be seen in the figure, the foundation reinforcing structure 1 according to the present embodiment has a desired horizontal length range from the rising portion to the top edge of the fabric foundation on both side surfaces 3a and 3b of the fabric foundation 2 made of unreinforced concrete. Aramid fiber sheets 4a and 4b, which are fiber sheets, are bonded. Although not shown, the fabric foundation 2 made of unreinforced concrete is installed on the footing as a concrete structure integral with the bottom plate footing, or directly on the cracked stone without footing. There is a case.

  The horizontal length to which the aramid fiber sheets 4a and 4b are bonded is preferably the entire length of the fabric foundation. However, since the fabric foundation usually has a protruding corner portion and an entering corner portion, What is necessary is just to carry out division | attachment adhesion | attachment, or to adhere | attach continuously, pressing down a corner part, especially an entrance corner part, with pressing members, such as a metal object.

  In order to construct the foundation reinforcing structure 1 according to this embodiment, first, as shown in FIG. 1 (b), the outdoor side ground is dug down to expose the outdoor side surface 3a of the fabric foundation 2.

  Next, after the outdoor side surface 3a is cleaned and a ground treatment such as unevenness adjustment of the concrete surface is performed as necessary, a primer and an undercoat adhesive are sequentially applied.

  Next, after adhering the aramid fiber sheet 4a, an overcoat adhesive is applied again from above, and finishing is performed by painting or the like as necessary.

  On the other hand, the same operation is performed indoors, that is, under the first floor. That is, as shown in FIG. 2B, the ground under the floor is dug down to expose the indoor side surface 3b of the fabric foundation 2.

  Next, after cleaning the indoor side surface 3b of the fabric foundation 2 and performing a ground treatment such as uneven adjustment of the concrete surface as necessary, a primer and an undercoat adhesive are sequentially applied.

  Next, after adhering the aramid fiber sheet 4b, the top coating adhesive is applied again from above.

  After the aramid fiber sheets 4a and 4b are constructed, the ground dug down is backfilled to complete the reinforcement work. In addition, what is necessary is just to select suitably from a well-known means about the kind of adhesive agent and the detailed adhesion | attachment method of the aramid fiber sheet 4a.

  As described above, according to the foundation reinforcing structure 1 according to this embodiment, since the aramid fiber sheets 4a and 4b bear the tensile stress generated in the cloth foundation 2 of unreinforced concrete, the cloth foundation 2 made of unreinforced concrete. It is possible to prevent the occurrence of bending cracks at the base top edge or the rising portion due to cracks, particularly, in-plane bending moment.

  Fig. 2 (a) shows the in-plane generated in the fabric foundation 2 due to the ground reaction force and the vertical load from the column that are insufficient in earth strength, or forced deformation due to non-settlement when the aramid fiber sheets 4a and 4b are not constructed. Bending moment diagram showing bending moment, Fig. (B) is a side view showing the bending cracks that occur in the fabric foundation 2 near the center column in Fig. (A), and Fig. (C) is the figure ( It is the side view which showed the mode of the bending crack which arises in the cloth foundation 2 in the column vicinity of the both ends of a).

  Moreover, according to the foundation reinforcement structure 1 which concerns on this embodiment, since the aramid fiber sheets 4a and 4b are adhere | attached on the both sides | surfaces of the fabric foundation 2, a tensile force balances and it is an out-of-plane direction, ie, the outdoor side or indoor side. There is no concern that any of them will bend and crack on the side.

  FIG. 3 is a horizontal cross-sectional view showing a state of bending cracks generated in the fabric foundation 2 due to bending in the out-of-plane direction when the aramid fiber sheet 4a is applied only to the outdoor side surface 3a of the fabric foundation 2. FIG.

  In order to demonstrate the effect of the foundation reinforcing structure according to the present invention, a bending force test was performed.

  First, as a result of conducting a bending force test in which a vertical load was applied to the vicinity of the center of an unreinforced concrete having a length of 3,000 mm, a height of 400 mm, and a width of about 120 mm, with the test body supported at both ends, 18 kN Destroyed.

  Next, as a result of performing a bending force test on a test body in which an aramid fiber sheet was bonded to the entire surface of one side of unreinforced concrete having the same shape, the yield strength was increased to about 25 kN, and the aramid fiber sheet was bonded to both surfaces. The test specimen (adhered to the entire surface and adhered to the other surface only in the vicinity of the center) showed a load resistance of 62 kN.

  By the way, in the same shape test specimen assuming the current standard RC foundation, it was destroyed at 42 kN, and it was proved that the aramid fiber sheet can be bonded to both sides to make the structure more resistant to bending than the RC foundation. .

  FIG. 4 shows the results of the bending force test described above.

(Second Embodiment)

  Next, a second embodiment will be described. Note that components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 5 is a view showing a foundation reinforcing structure according to the present embodiment. As can be seen from the figure, the foundation reinforcing structure 11 according to this embodiment includes a pair of aramid fibers that are fiber sheets in the vicinity of the rising portion and the top end of the outdoor side surface 3a of the cloth foundation 2 made of unreinforced concrete. The sheets 14a and 14a are bonded in two upper and lower stages, and the aramid fiber sheet 14b is attached to the indoor side surface 3b so that the intermediate height of the pair of aramid fiber sheets and the height above the ground surface is the bonding position. Is adhered.

  The horizontal length for bonding the aramid fiber sheets 14a and 14a and the aramid fiber sheet 14b is preferably the entire length of the cloth foundation, but the cloth foundation usually has a protruding corner portion and an ingress corner portion. In such a case, it may be divided and bonded as appropriate, or may be continuously bonded while pressing corners, particularly corners, with a pressing member such as a hardware.

  As described above, the aramid fiber sheet 14b is positioned so that it is at an intermediate height between the pair of aramid fiber sheets 14a and 14a and at a height equal to or higher than the ground surface, but the aramid fiber sheets 14a and 14a. The intermediate height may be a range between the centers of the widths, for example, and the bonding position of the aramid fiber sheet 14b may be determined so that the center of the width of the aramid fiber sheet 14b is within the range.

  In the present embodiment, since the ground on the indoor side is not dug down, the lower edge of the aramid fiber sheet 14b is set to be equal to or greater than the ground surface.

  In order to construct the foundation reinforcing structure 11 according to the present embodiment, first, the outdoor side ground is dug down to expose the outdoor side surface 3 a of the fabric foundation 2.

  Next, after the outdoor side surface 3a is cleaned and a ground treatment such as unevenness adjustment of the concrete surface is performed as necessary, a primer and an undercoat adhesive are sequentially applied.

  Next, after the aramid fiber sheets 14a and 14a are bonded in two upper and lower stages as described above, an overcoat adhesive is applied again from above, and finishing is performed by painting or the like as necessary.

  On the other hand, the aramid fiber sheet 14b is bonded to the indoor side surface 3b of the fabric foundation 2 at a height equal to or higher than the ground surface without digging the ground under the floor on the indoor side, that is, under the first floor.

  That is, the indoor side surface 3b of the fabric foundation 2 is cleaned, and after performing a ground treatment such as uneven adjustment of the concrete surface as necessary, a primer and an undercoat adhesive are sequentially applied.

  Next, after adhering the aramid fiber sheet 14b, the top coating adhesive is applied again from above.

  After the aramid fiber sheets 14a and 14a are constructed, the ground dug down on the outdoor side is backfilled to complete the reinforcement work. In addition, what is necessary is just to select suitably from a well-known means about the kind of adhesive agent, and the detailed adhesion | attachment method of the aramid fiber sheets 14a and 14a and the aramid fiber sheet 14b.

  As explained above, according to the foundation reinforcing structure 11 according to the present embodiment, a pair of aramid fiber sheets 14a in the vicinity of the rising portion and the vicinity of the top end of the outdoor side surface 3a of the fabric foundation 2 made of unreinforced concrete. 14a is bonded in two upper and lower stages, and the aramid fiber sheet 14b is bonded to the indoor side surface 3b so that the intermediate height of the pair of aramid fiber sheets and the height above the ground surface is the bonding position. As a result, the same effects as those of the first embodiment described above can be obtained, and ground excavation work on the indoor side is not required. Therefore, workability under the first floor is greatly improved, and accordingly, There is no need to peel off floorboards or remove some walls, thus making renovation work more efficient without changing the lives of residents. It made.

  Bending cracks due to in-plane bending moments and bending cracks due to out-of-plane bending are the same as in the first embodiment, but bending cracks due to in-plane bending moments can be seen in Figs. 2 (b) and 2 (c). In addition, the aramid fiber sheets 4a and 4a, which are at the rising portion of the fabric base 2 or near the top end and are arranged in two upper and lower stages, can reliably prevent the occurrence of such bending cracks.

  In addition, it goes without saying that bending cracks due to out-of-plane bending shown in FIG. 3 are similarly prevented by the aramid fiber sheet 4b bonded to the indoor side.

It is a figure of the foundation reinforcement structure concerning a 1st embodiment, (a) is a side view and (b) is a sectional view which meets an AA line. The in-plane bending moment diagram and the figure which shows the bending crack by it. The figure which showed the bending crack by the out-of-plane deflection. The graph which showed the result of the bending force test. It is a figure of the foundation reinforcement structure which concerns on 2nd Embodiment, (a) is a side view, (b) is sectional drawing which follows a BB line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Foundation reinforcement structure 2 Cloth foundation 3a, 3b Side face 4a, 4b, 14a, 14b of cloth foundation Aramid fiber sheet (fiber sheet)

Claims (3)

By bonding the fiber sheet to both sides of the fabric foundation made of unreinforced concrete in the desired horizontal length range from the rising edge to the top edge of the fabric foundation, cracks due to in-plane bending moment generated on the fabric foundation and out-of-plane A basic reinforcement structure characterized by being configured to suppress cracking due to bending. Among the outdoor side surfaces of the fabric foundation made of non-reinforced concrete, a pair of fiber sheets are bonded in two upper and lower stages near the rising portion and near the top end, and the ground surface is at an intermediate height between the pair of fiber sheets A basic reinforcing structure characterized in that a fiber sheet is bonded to the side surface on the indoor side so that the above height is the bonding position. The basic reinforcement structure according to claim 1 or 2, wherein the fiber sheet is an aramid fiber sheet.

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