JP4162698B1 - Reinforcing member and reinforcing method for concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a relatively inexpensive reinforcing member for a concrete structure having excellent adhesion to the concrete structure.
SOLUTION: A fiber sheet 1 adhered to a surface of a concrete structure to be reinforced, and embedded in the concrete structure from the fiber sheet at a predetermined interval, and the fiber sheet 1 side is divided into a plurality of radial shapes. It is characterized by comprising a fiber anchor 2 that is spread and attached to the upper surface of the fiber sheet 1, and a fiber sheet piece 3 that is attached to cover the radial spread of the fiber anchor 2.
[Selection] Figure 1

Description

  The present invention relates to a reinforcing member and a reinforcing method for a concrete structure, and more particularly to a reinforcing member and a reinforcing method for a concrete structure using a fiber sheet.

As a method for reinforcing a concrete structure such as a foundation of a building structure, a reinforcing method in which a fiber sheet is bonded to a resin is known (see Patent Document 1 and Patent Document 2). The reinforcement of a concrete structure by continuous fiber sheet bonding has features such as easy construction and a short construction period, as compared with the case where reinforcement is performed using special reinforcing metal fittings. Moreover, it has the advantage that a flexible reinforcement design is possible by increasing the amount of fiber and the number of laminated layers.
However, when the adhesion between the concrete structure and the fiber sheet is poor, there is a problem in that the interfacial peeling occurs between the fiber sheet and the concrete structure, and the strength decreases.

  In addition, carbon fiber sheets and aramid fiber sheets, which are usually high strength and high elasticity, are often used as the fiber sheets, but carbon fiber sheets and aramid fiber sheets have a problem that they are relatively expensive. ing. On the other hand, the glass fiber sheet is used for reinforcement in Japan, because the Young's modulus is too low and the bending reinforcement efficiency is inferior despite the material unit price being significantly cheaper than carbon fiber sheets and aramid fiber sheets. There are few. However, the glass fiber sheet is more than twice as long as the carbon fiber sheet or the aramid fiber sheet, and has a high toughness ratio, so it is considered that the seismic reinforcement effect can be sufficiently obtained.

JP 2004-232276 A JP 2001-90255 A

Conventional reinforcement of a concrete structure with a fiber sheet has a problem in that the strength decreases when the adhesion between the concrete structure and the fiber sheet is poor. There is also a problem that it is relatively expensive.
The present invention has been made in view of such circumstances, and an object thereof is to realize a relatively inexpensive reinforcing member for a concrete structure that is excellent in adhesion to a concrete structure and a reinforcing method using the reinforcing material. Is.

In order to solve the above-described problems, a concrete structure reinforcing method according to the present invention includes an injection hole opening sub-step of opening a plurality of injection holes for filling a resin along a crack of a concrete structure to be reinforced, and the injection hole. A sealing sub-process for closing a gap other than a resin, and an injection hole resin filling sub-process for filling the injection hole with resin and curing for a predetermined time, and filling the resin in the vicinity of the crack, and the concrete An adhesive primer sub-process for applying an adhesive to the surface of the structure, a fiber sheet sticking sub-process for sticking the fiber sheet to the surface of the concrete structure to which the adhesive is primed, and the fiber sheet applied An adhesive intermediate coating sub-process for applying the adhesive again while removing air bubbles in the fiber sheet, and an adhesive further applied on the adhesive applied in the adhesive intermediate coating sub-process. An adhesive overcoating sub-process to fabricate and cure, and a fiber sheet adhering process for adhering the fiber sheets of a plurality of layers by repeating each sub-process as necessary, and immediately after the fiber sheet adhering process is completed An embedding hole drilling sub-process for drilling an embedding hole for embedding the fiber anchor at a plurality of locations on the fiber sheet, and an embedding hole cleaning sub-process for sucking and cleaning chips inside the embedding hole; A fiber anchor insertion sub-step for injecting resin into the embedding hole and inserting the fiber anchor to a predetermined length, and after a predetermined curing, the remaining portions coming out from the embedding hole of the fiber anchor into a plurality of fibers large enough to cover a split the fiber sheet top surface sticking Keru fibers sticking spread in a radial sub-by step, the fibers adhered spread radially by the fibers sticking substep And a fiber coating sub step of impregnating the adhesive paste fiber sheet piece, the surface of the concrete structure pasted the fiber sheet and a fiber anchor embedding affixing crowded embedding the fibers anchor It is characterized by having.

  In order to solve the above problems, a reinforcing member for a concrete structure according to the present invention includes a fiber sheet bonded to the surface of a concrete structure to be reinforced, and a predetermined interval from above the fiber sheet to the concrete structure. A fiber anchor that is placed and embedded and the fiber sheet side is divided into a plurality of pieces and spreads radially and is attached to the upper surface of the fiber sheet; and a fiber sheet piece that is attached to cover the radial spread of the fiber anchor. It is characterized by having.

  Since the present invention is configured and functions as described above, it is a relatively simple and easy work process, does not require a large-scale mechanical device, and can be used for a concrete structure that can be inexpensively and reliably reinforced in a short construction period. A reinforcing method can be realized, and a reinforcing member for a concrete structure that can be reliably reinforced at a low cost with a relatively simple configuration and a small number of materials can be realized.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a reinforcing member for a concrete structure and a reinforcing method according to the present invention will be described in detail with reference to the drawings and diagrams.

FIG. 1 and FIG. 2 are a side view and a cross-sectional view of a specimen for conducting a bending reinforcement effect verification experiment on the reinforcing member of the present invention and a comparative sample to be compared with the reinforcing member. 1 and 2, reference numeral 1 denotes a fiber sheet, reference numeral 1-1 denotes a first-layer fiber sheet, and reference numeral 1-2 denotes a second-layer fiber sheet. Reference numeral 2 denotes a fiber anchor, and reference numeral 3 denotes a fiber sheet piece covering the fiber anchor. Reference numeral 10 is a specimen for a verification experiment of the present invention, reference numeral 11 is an axial streak, reference numeral 12 is a shear bar, reference numeral 13 is a fulcrum that supports the specimen 10 during the test, and reference numeral 14 is a load application point. H1 represents the height of the first-layer fiber sheet, and h2 represents the height of the second-layer fiber sheet.
FIG. 3 is a chart showing the types of the specimen 10. The specimen 10 was a T-shaped cross-section beam with an under-reinforcing bar ratio assuming a cloth foundation of an existing wooden building. In order to reproduce a foundation having crack damage, five 125 mm-spaced crack guide joints are provided in the bending span of the central portion in advance so that all the specimens 10 are in the same cracked state, which is about 0.2 mm wide. 4 point bending loading was performed until it became. There are six specimens 10 of Type A to F.
After the initial crack was introduced, cracks were repaired by injecting epoxy resin into all the specimens 10. Thus, Type A was only reinforced with epoxy resin, and Type B to F were reinforced by adhering the glass fiber sheet 1 after the epoxy resin was injected.
Furthermore, for TypeE and F corresponding to the embodiment of the present invention, six fiber anchors 2 are installed at intervals of 450 mm so as to suppress the peeling of the glass fiber sheet 1.

Originally, it is desirable to reinforce by bending the sheet 1 to the bottom surface of the tension side for bending reinforcement, but the existing wooden building cloth foundation that is the subject of this test has a narrow work space and restricts reinforcement work. Since it is received, it is limited to the construction on the side and only on one side, so the pasting position as shown in FIGS. 1 and 3 was adopted.
The glass fiber sheet 1 is obtained by processing glass fibers into a lattice-like knitted sheet. The fiber anchor 2 is formed by bundling glass fiber rovings, spreading an umbrella portion radially and impregnating the sheet with a sheet. The characteristics of concrete, rebar, glass sheet and resin adhesive are shown in the chart of FIG.

Here, the procedure of an embodiment of the method for reinforcing a concrete structure of the present invention will be described. FIG. 5 shows a processing flowchart of this reinforcing method.
(1) Resin filling process Several injection holes for resin filling are opened along the cracks of the concrete structure (injection hole opening sub-process: S1), and the gaps other than the injection holes are sealed (sealing sub-process: S2). ). Next, a jig for filling the construction resin is installed in the injection hole, and the epoxy resin is filled using a dedicated injection device (injection hole resin filling sub-step: S3).
When about 5 hours have elapsed since the start of resin injection only on the sheet bonding construction surface, the injection tool is removed, the surface of the concrete structure is subjected to surface treatment, and the process proceeds to sheet bonding construction.

(2) Fiber sheet bonding step This is a step of bonding the glass fiber sheet 1 to the surface of a concrete structure in which an epoxy resin is filled in the cracked portion.
The epoxy adhesive is spread over two layers and the glass fiber sheet 1 is pasted (fiber sheet pasting sub-step: S5) after the primer is subbed (adhesive primer sub-step: S4). After pasting, the epoxy adhesive is applied again from the top of the sheet, and bubbles in the sheet are removed using a defoaming roller (adhesive intermediate coating sub-step: S6). Finally, an epoxy adhesive is applied (adhesive overcoating sub-step: S7) and cured in air.
Next, it is determined whether or not the glass fiber sheet 1 is to be bonded in plural layers (S8). When the glass fiber sheets 1 are laminated, the process returns to S4 and the above sub-process is repeated to bond the glass fiber sheets 1 in the plural layers.

(3) Fiber anchor embedding process Immediately after the glass fiber sheet 1 is stuck, the fiber anchor 2 is embedded by 50 mm.
First, immediately after completion of the glass fiber sheet bonding step, the embedding holes for embedding the fiber anchor 2 are perforated at a plurality of locations on the fiber sheet at a predetermined interval (embedding hole perforating sub-step: S9).
Next, dust inside the embedded hole is sucked and cleaned (embedded hole cleaning sub-process S10).
Further, resin is injected into the embedding hole, and the tip of the fiber anchor 2 is penetrated through the glass fiber sheet 1 and embedded in the concrete structure to a predetermined length (fiber anchor insertion sub-step: S11).
Then, after predetermined curing, the remaining portion of the fiber exposed to the outside from the embedding hole of the fiber anchor 2 is divided into a plurality of pieces and spread radially on the upper surface of the fiber sheet and pasted (fiber pasting sub-step: S12).
Next, a glass fiber sheet piece (100 * 100 mm) 3 is attached so as to cover the fiber that is radially spread and attached, and impregnated with an epoxy adhesive (fiber coating sub-step: S13).

  Through such a series of steps, the method for reinforcing a concrete structure according to the present invention is realized, and the bending strength and deformation performance of the structure are improved by a relatively simple and easy operation as will be described later. More effective reinforcement can be performed by suppressing peeling of the resin. Specimens on which the reinforcing method of the present invention was implemented are TypeE and TypeF.

Again, we return to the test results based on the specimen.
For the specimen 10 that has been repaired and reinforced, Type A to E are subjected to an incremental 4-point bending load test, and Type F is the displacement of the point where the slope of the load-deflection curve has changed according to the test result of Type E, which is the same reinforcement type. The loading step was set so as to be an odd multiple thereof, and loading was repeated three times for each step. During the loading test, the strain of the sheet, rebar and concrete, vertical displacement at the center of the span, and crack width at the bottom of the specimen were measured.

The deformation | transformation and destruction property are shown about TypeA-D compared with TypeE and TypeF of embodiment of this invention.
Although the crack width expanded in advance at the initial crack introduction site, the cracks gradually disseminated in Type B to D, where the sheet reinforcement was performed, and the bending cracks progressed over the entire loading span.
With respect to the failure of the specimen, with unreinforced Type A, only the deflection and crack width increased without increasing the load, and loading was terminated when the deflection exceeded 4 mm. In types B to D where sheet reinforcement was performed, the sheet was largely peeled off at each maximum load, and the load decreased. At this point, loading was completed.
The type of failure of Type B to D was not a bending compression failure type that reached the end by crushing the upper edge side concrete, but a release failure type that caused the sheet to peel and reached the end. In addition, all the specimens did not eventually break the sheet. From this, it is considered that the bending strength of the reinforcing specimen depends on the adhesion strength of the sheet.
FIG. 6 shows the load-deflection relationship at the center of the span. It can be confirmed that the bending strength and toughness are remarkably improved by sheet reinforcement. Further, the reinforcing effect depends on the reinforcing amount of the sheet.

Next, the relationship between the sheet distortion and the peeling state in these specimens 10 is shown. FIG. 7 shows the load-sheet strain relationship at the lowermost edge of the center of the span of Type B to F. From the figure, it can be seen that in Type B to D, the sheet contributes to the tensile resistance because the distortion of the sheet increases after the occurrence of the crack.
The sheets adhered to one side of Type B to D were gradually peeled off from the concrete as the load increased. Sheet peeling occurred in a streak pattern along the cracks in the concrete that occurred between the loading spans, and then the peeling area gradually expanded in the direction of the fulcrum. FIG. 8 shows a concrete crack and a state of peeling of the sheet.

Next, the deformation and destructive properties of Type E and F corresponding to the embodiment of the present invention are shown.
The load-deflection relationship of TypeE and TypeF is shown in FIG. In TypeE, after the load 92 kN, the ship owner increased and decreased 3 lines, and at 95 kN, the sheet edge part (fulcrum side) was completely peeled from the concrete and destroyed. As a result, it has been clarified that the fiber anchor can significantly improve the bending strength and toughness by suppressing the peeling of the sheet.
TypeF was repeatedly loaded with the displacement at the point where the slope of the load-deflection curve changed from the test result of TypeE as the standard displacement ∂y = 1.32mm. It can be confirmed that the behavior is almost the same as that of Type E until the displacement is 17∂y (P = 89.5 kN). When the displacement is increased to 19 ∂y, a large amount of peeling occurs, and when it is attempted to increase to 21 ∂y, the sheet edge (fulcrum side) completely peels from the concrete along with a loud peeling sound. The destruction type was the same as TypeE.

Next, the relationship between the sheet distortion and the peeling state in the specimen of the embodiment of the present invention is shown.
From the load-sheet strain curve shown in Fig. 7, TypeE and TypeF with fiber anchor installed have increased strain at maximum load compared to TypeB and C applied on one side, and are equivalent to Type D on both sides. I understand. From this, it can be seen that TypeE and F, in which the peeling of the sheet that greatly affects the proof stress is delayed by the installation of the fiber anchor, makes the sheet reinforcing effect more effective.
In addition, after the sheet peeling occurred like streaks along the cracks between the loading spans as in Type B to D, the peeling area gradually expanded in the direction of the intersection. However, in TypeE and F, one fiber anchor at the fulcrum end at one end sheared at the interface between the existing concrete and the glass fiber sheet, and the sheet completely separated from the concrete.
It can be confirmed that the cracks generated in Type E are shear cracks from the loading point toward the fulcrum with respect to the bending cracks generated in Type B to D where the fiber anchor is not installed. In order to verify the bending reinforcement effect, the specimen was prepared so that the bending fracture precedes, but the sheet continues to bear the tensile force even after the peeling of the sheet occurs due to the installation of the fiber anchor, so that the bending strength increases. At the same time, it is considered that shear cracks occurred.

Next, the reinforcing effect is compared for each specimen.
(1) Yield and ultimate yield strength The definitions of various values described below are shown in FIG.
Relative comparison based on the yield strength (Pya) of Type A with the yield strength as Py (Fig. 10) when the lowermost reinforcing bar at the crack occurrence point yields, and the point where the load of each specimen is maximum 11 is shown in FIG. 11, which is a relative comparison based on the ultimate proof strength of Type A, with the ultimate proof strength Pu (FIG. 10). With respect to the yield strength, except for TypeC, the relative relationship between the specimens is the same as the ultimate strength, and it can be seen that the yield strength is increased by 1.4 to 1.9 times due to sheet reinforcement. The ultimate proof stress was the largest for TypeD, with sheets on both sides, and 3.8 times that of TypeA. TypeE and F have a significant increase in ultimate yield strength compared to TypeC with the same amount of sheet reinforcement, so the fiber anchor delamination suppression effect is clear.

(2) Deformable touch The displacement at the center of the span during yield strength is δy, the displacement at maximum load is δu, and the value obtained by dividing δu by δy is the plastic modulus μ (μ = δu / δy). A comparison was made. FIG. 12 shows the ratio of plasticity ratios compared with the plasticity ratio (μa) of Type A, together with the plasticity ratio of each type.
In addition, in the load-deflection curve, the area formed by the curve up to the maximum load is defined as energy absorption capacity E (FIG. 10), and a relative comparison based on Type A energy absorption capacity (Ea) is shown in FIG. Show.
From the figure, it can be confirmed that TypeE has the largest energy absorption capacity of about 20 times that of TypeA, and TypeF, which has been repeatedly loaded, has the same energy absorption capacity as TypeD with sheets on both sides. From these, it is clear that the energy absorption capacity is increased due to the sheet peeling suppression effect by the fiber anchor.

Figures 14 and 15 show the results of comparing the calculated ultimate proof stress based on the RC bending theory and the experimental value, assuming that there are two types of ultimate strain of the sheet, and that the plane retention law of the cross section holds until the ultimate time. Show. That is, the calculated value (I) is the value when the upper edge concrete strain reaches the ultimate strain of concrete in Type A, and the time when the bottom end sheet strain reaches 2.2% of the design fracture strain for Type B to F. The bending strength was calculated assuming that each sheet is in the final state and the sheet behaves as a completely synthetic cross section without peeling.
As a result, the ratio of the experimental value and the calculated value (I) of Type B to D without the fiber anchor is 0.43 to 0.59, and the ratio of Type AE and F with the fiber anchor is 0.62 to 0 .68, both values were too small. This confirms that the ultimate sheet strain is less than the design breaking strain and that the fiber anchor is installed to delay sheet peeling and increase the tensile resistance.

On the other hand, the calculated value (II) is a calculated value of the bending strength based on the actual measured value of the sheet strain at the maximum load. The final sheet strain is 0.8 to 1.3% corresponding to 40 to 60% of the breaking strain, and the ratio between the actual drum value and the calculated value (II) based on this is 0.74 to 1.34. The result was closer to the experimental value than the calculated value (I). In particular, in TypeAE and F with a fiber anchor installed, the ultimate strain of the sheet was 1.2 to 1.3%, and the calculation using this was in good agreement with the experimental value.
From the above, it is considered that the ultimate bending strength can be accurately estimated based on the RC bending theory if the delamination strain at the end of the sheet is found.

  As described above, when the reinforcing member of the concrete structure of the present invention is used, or according to the reinforcing method of the concrete structure of the present invention, by installing the fiber anchor, peeling of the glass fiber sheet is suppressed, In addition, since the sheet can bear the tensile force even after the separation progresses, a sufficient improvement in yield strength can be obtained with a relatively inexpensive configuration and a simple man-hour. The work does not require a large-scale mechanical device or a skilled worker, and is advantageous in that respect.

  As described above, the present invention has a remarkable effect in repairing concrete structures, and thus has a wide range of possibilities for use in a wide range of construction and construction industries.

It is a side view of a specimen for carrying out a bending reinforcement effect verification experiment on a reinforcing member of the present invention and a comparative sample to be compared therewith. It is sectional drawing of the test body shown in FIG. It is a chart which shows the kind of specimen for an effect test of the present invention. 4 is a chart showing characteristic values of materials used for the specimen shown in FIG. 3. It is a flowchart of the reinforcement method of this invention. It is a chart which shows the load-deflection relationship of the span center part in the test body shown in FIG. It is a chart which shows the load-sheet distortion | strain relationship of the span center lowermost edge in the test body shown in FIG. It is a chart which shows the concrete crack in the test body shown in FIG. 3, and the peeling condition of a sheet | seat. It is a graph which shows the load-deflection relationship of the span center part in the test body corresponding to this invention. It is a chart which shows the definition of various values which show reinforcement effect 4 is a chart comparing yield load and ultimate load for each specimen shown in FIG. 3. FIG. 4 is a chart comparing plasticity ratios for each specimen shown in FIG. 3. FIG. 4 is a chart comparing energy absorption capacity for each specimen shown in FIG. 3. FIG. 4 is a chart comparing the reinforcing effects for each specimen shown in FIG. 3. FIG. 4 is a chart comparing calculated values of ultimate strength for each specimen shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass fiber sheet 2 Fiber anchor 3 Fiber sheet piece 10 Specimen 11 Axial direction muscle 12 Shear strength 13 Support point 14 Load application point

Claims (6)

An injection hole opening sub-process for opening a plurality of injection holes for filling the resin along the cracks in the concrete structure to be reinforced, a sealing sub-process for closing a gap other than the injection hole with resin, and a resin in the injection hole A filling process for filling and curing for a predetermined time, and filling a resin in the vicinity of the crack;
Adhesive primer sub-step for applying an adhesive to the surface of the concrete structure, fiber sheet sticking sub-step for sticking the fiber sheet to the surface of the concrete structure primed with the adhesive, and the pasted Applying adhesive on the fiber sheet again while removing air bubbles in the fiber sheet, and applying the adhesive on the adhesive applied in the adhesive intermediate coating sub-process and curing the adhesive. An adhesive overcoating sub-step, and a fiber sheet bonding step in which the sub-steps from the adhesive undercoating sub-step to the adhesive over-coating sub-step are repeated as necessary to bond the fiber sheets of a plurality of layers. When,
Immediately after completion of the fiber sheet bonding step, an embedding hole drilling sub-process in which embedding holes for embedding the fiber anchors are drilled at a plurality of locations on the fiber sheet, and dust inside the embedding holes is sucked and cleaned. A sub-step for cleaning the embedding hole, a sub-step for inserting the fiber anchor into the embedding hole and inserting the fiber anchor to a predetermined length, and after a predetermined curing, exit from the embedding hole of the fiber anchor. and sticking Keru fiber sticking substep spread radially dividing the remainder to a plurality of fibers on the upper surface of the fiber sheet are, the fibers sticking to the extent that the sub step covering said fibers adhered spread radially magnitude of and a fiber coating sub step of impregnating the adhesive paste fiber sheet piece, phi on the surface of the concrete structure pasted the fiber sheet Method for reinforcing concrete structures and having a fiber anchor embedding affixing crowded embedding the over anchor.   2. The method for reinforcing a concrete structure according to claim 1, wherein the fiber sheet is a glass fiber sheet obtained by knitting glass fibers in a lattice shape and processing into a sheet shape.   The method for reinforcing a concrete structure according to claim 1 or 2, wherein the resin used in the resin filling step or the fiber anchor embedding step is an epoxy resin.   The method for reinforcing a concrete structure according to any one of claims 1 to 3, wherein an adhesive used in the fiber sheet bonding step or the fiber anchor embedding step is an epoxy adhesive. A fiber sheet bonded to the surface of the concrete structure to be reinforced,
A fiber anchor embedded in the concrete structure at a predetermined interval from above the fiber sheet, and the fiber sheet side is divided into a plurality of pieces and radially spread and attached to the upper surface of the fiber sheet;
A reinforcing member for a concrete structure, comprising: a fiber sheet piece attached to cover a radial spread of the fiber anchor.   6. The reinforcing member for a concrete structure according to claim 5, wherein the fiber sheet is a glass fiber sheet obtained by knitting glass fibers in a lattice shape and processing into a sheet shape.