KR101013088B1 - Shear reinforcing method and bending and shear simultaneously reinforcing method of a concrete structure - Google Patents

Abstract

PURPOSE: A method for simultaneously reinforcing the bending and shear resistances of a concrete structure is provided to achieve bending and shear reinforcement of a concrete structure at the same time by employing reinforcing materials against bending stress and anchors against shear stress. CONSTITUTION: A method for simultaneously reinforcing the bending and shear resistances of a concrete structure is as follows. A degraded surface of a concrete structure(C) is arranged. The arranged surface is repaired with mortar(M). A reinforcing material is installed in the site of the concrete structure where bending stress acts. An anchor(A) is installed in the site of the concrete structure where shear stress acts.

Description

Shear reinforcing method and bending and shear simultaneously reinforcing method of a concrete structure}

The present invention relates to the simultaneous reinforcement of bending and shearing of concrete structures.

In general, concrete structure reinforcement methods include large attachment method, cross-section expansion method.

Here, the attachment method is a steel plate attachment method, a fiber sheet reinforcement method, a fiber plate reinforcement method and the like.

The steel plate attachment method is a method of reinforcing using a steel plate, the weight of the steel sheet is large, and heavy equipment is required during construction.

In addition, the corrosion of the steel sheet itself is concerned, there is a problem of interfacial peeling due to the lack of breathability due to the sealing phenomenon.

In addition, the fiber sheet reinforcement method has a problem that the construction is difficult compared to the reinforcing performance, the quality is dependent on the skill of the operator.

In addition, due to the entire construction lacks breathability, there is a difficulty in maintenance.

In addition, the fiber board reinforcement method is excellent in material properties, but there is a limit in the adhesion performance, such as end peeling, because the adhesive performance with the structure to be reinforced is dependent only on the epoxy adhesive.

In particular, when the entire construction lacks breathability, there is a difficulty in maintenance.

In order to overcome these limitations, we are developing additional reinforcing steel and reinforcing materials that impart breathability.

On the other hand, the cross-sectional expansion method is a method for reinforcing the concrete structure by further expanding the cross section in addition to the concrete structure, there is a steel expansion method, reinforcement buried method, concrete expansion method.

Double concrete steaming method is a method widely used for flexural or shear reinforcement, grouting the base material, spraying by shotcrete method, and bonding or spraying or spraying high performance concrete mortar with good fluidity and adhesion. It is a construction method.

However, depending on the site conditions, there is a problem in the adhesion between the concrete structure and the expanded mortar, which is often peeled, it is difficult to obtain a sufficient reinforcing effect.

In addition, it is often impossible to apply realistically due to the limitation of the internal space.

Therefore, the present invention was devised to solve the problems as described above, by installing the anchor in the site where the shear stress acts on the concrete structure by shear reinforcement, concrete structure to obtain the shear reinforcement effect of the concrete structure The purpose is to provide a shear reinforcement method.

In addition, after flexural reinforcement using the reinforcement material on the surface of the site where the bending stress is applied to the concrete structure, the shear reinforcement by installing the anchor at the site where the shear stress is applied to the concrete structure, the bending and shear reinforcement effect of the concrete structure The purpose is to provide a simultaneous reinforcement method for bending and shearing concrete structures to obtain the

Shear reinforcement method of a concrete structure according to the present invention for achieving the above object comprises the steps of cleaning the deteriorated surface of the concrete structure; Repairing a cross section using mortar on the cleaned surface; Characterized in that it comprises the step of installing the anchor on the site where the shear stress of the concrete structure acts.

In addition, the simultaneous bending and shear reinforcement method of the concrete structure according to the present invention for achieving the above object comprises the steps of cleaning the deteriorated surface of the concrete structure; Repairing a cross section using mortar on the cleaned surface; Fixing the reinforcement to a portion at which bending stress of the concrete structure acts; Characterized in that it comprises the step of installing the anchor in the shear stress acting portion of the concrete structure.

As described above, the shear reinforcement method of the concrete structure according to the present invention has an advantage that the shear reinforcement effect of the concrete structure can be obtained by installing the anchor at the site where the shear stress acts on the concrete structure.

In addition, in the simultaneous reinforcement method of bending and shearing concrete structures according to the present invention after the reinforcement using the reinforcement on the surface of the site where the bending stress acts on the concrete structure, anchors are installed on the site where the shear stress is applied to the concrete structure By shear reinforcement, there is an advantage that the bending and shear reinforcement effect of the concrete structure can be simultaneously obtained.

1 is an exemplary view showing a shear reinforcement state of a concrete structure according to the present invention,
2 is an exemplary view showing a shear repair, reinforcement state of a concrete structure according to the present invention;
3 is an exemplary view showing a state of simultaneous reinforcement of bending and shear of a concrete structure according to the present invention,
Figure 4 is an exemplary view showing the bending and shear shear repair, reinforcement state of the concrete structure according to the invention.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

1 is an exemplary view showing a shear reinforcement state of a concrete structure according to the present invention, Figure 2 is an exemplary view showing a shear repair, reinforcement state of a concrete structure according to the present invention.

As shown in these drawings, the shear reinforcement method of the concrete structure according to the present invention comprises the steps of cleaning the deteriorated surface of the concrete structure (C); Repairing a cross section using mortar (M) on the clean surface; Comprising the step of installing the anchor (A) to the site where the shear stress of the concrete structure (C) acts.

In addition, the anchor (A) is made of any one or at least two materials of metal or FRP, and is composed of a chemical anchor (chemical anchor) or a mechanical anchor (mechanical anchor).

The anchor (A) is installed at a predetermined angle, depth, interval, diameter on the site where the shear force is applied.

That is, the insertion angle of the anchor: in the range of 30 to 150 degrees in the direction of the sign crack

Insertion depth of anchor: at least d / 2 (d: effective depth (distance from the center of longitudinal tension bar to the concrete compression edge)), up to the upper tension bar

Anchor spacing: max d or less

Anchor diameter: diameter of the change value depending on the characteristics of the concrete structure

Shear reinforcement method of a concrete structure according to the present invention made of a configuration as described above to install the anchor (A) at a predetermined angle, depth, interval, diameter on the site where the shear stress of the concrete structure (C) acts shear reinforcement By implementing, there is an effect of reinforcing the shear of the concrete structure (C).

On the other hand, Figure 3 is an exemplary view showing the simultaneous reinforcement of the bending and shear of the concrete structure according to the invention, Figure 4 is an illustration showing the simultaneous repair and reinforcement of the bending and shear of the concrete structure according to the present invention.

As shown in these drawings, the simultaneous bending and shearing reinforcement method of the concrete structure according to the present invention comprises the steps of cleaning the deteriorated surface of the concrete structure (C); Repairing a cross section using mortar (M) on the clean surface; Fixing the reinforcing material (R) to a site where the bending stress of the concrete structure (C) acts; Comprising the step of installing the anchor (A) to the site where the shear stress of the concrete structure (C) acts.

In addition, the reinforcing material (R) is composed of any one or at least two or more of the metal or FRP.

And, the anchor (A) is made of any one or at least two or more materials of metal or FRP, and is composed of a chemical anchor (chemical anchor) or a mechanical anchor (mechanical anchor).

Simultaneous reinforcement of the bending and shearing of the concrete structure according to the present invention having the configuration as described above after the reinforcement using the reinforcement (R) to the site where the bending stress acts on the concrete structure (C), the concrete structure ( Shear reinforcement is performed by installing anchor (A) in the direction of sinusoidal crack, which is the site of shear stress in C), which has the effect of simultaneously reinforcing the bending and shear of concrete structure (C).

[Example]

Simultaneous Reinforcement of Slab Flexural Shear Using Koslem GP and Chemical Anchor

(Simultaneous moment and shear Strengthening of RC Slabs and Shells by using COSREM-GP and chemical anchor)

Introduction

Recently, a lot of reinforcement of the existing member force due to the increase of load according to the external environment changes, cross-sectional damage of the existing member, etc., but the bending reinforcement is mainly performed than the shear.

In particular, shear reinforcement of plate structures such as slabs, walls, etc. of box structures is performed by expanding member sections or constructing additional structures, but this situation is not applicable due to many difficulties in the field conditions.

Accordingly, this experiment was conducted to investigate the effects of simultaneous bending and shear reinforcement of plate structures that can be constructed in consideration of site conditions.

2. Experiment Outline

2.1 Plan the specimen

In this experiment, the specimen without shear reinforcement (CONT-S) and the shear reinforcement (RS-ST) with shear reinforcement (RS-ST) with a length of 3m and a cross section of 60cm x 30cm (RS-) were used. CA) was fabricated and compared to examine the reinforcing effect.

In addition, RS-CA specimens were prepared by dividing the RS-CA-45S, RS-CA-45L, RS-CA-90 to determine the amount of reinforcement according to the insertion angle and length of the chemical anchor.

The specifications of each specimen are as follows.

① CONT-S (no reinforcement)

② RS-ST (Stirrup Reinforcement)

③ RS-CA-90 (chemical anchor 90 ° reinforcement)

④ RS-CA-45S (chemical anchor 45 ° reinforcement)

⑤ RS-CA-45L (chemical anchor 45 ° and = 280mm reinforcement)

2.2 Material test

The reinforcement was performed using a COSREM-GP panel and a chemical anchor. The mechanical properties of each were as follows.

Product Name Size (mm) Design strength Remarks concrete - fck = 19.8 Mpa 28 days compressive strength rebar D22, D10 SS400 COSREM-GP BxH = 100x35 500 Mpa Anchor Φ = 10.7 SS400

2.3 Experimental Method

In order to induce shear failure using a 50ton capacity actuator, two-point force was applied until failure by load control method. LVDT, COSREM-GP, lower main reinforcing bar, shear reinforcing bar and shear reinforcing anchor at the point of center and center Strain-gauge was installed.

[Experimental foreground photo]

3. Experimental Results

The fracture load of the non-reinforced CONT-S was 38.6 ton, and the RS-ST fracture load of the test specimen reinforced with reinforcing bars D10 @ 150 was 40.4 ton, and that of RS-CA-90 was 41.3 ton and RS-CA. The -45 specimens were destroyed at 47.6 tons.

Experiment Breaking Strength (Ton) Breaking load increase Remarks CONT-S 38.6 - RS-ST 40.4 4.66% ㅿ = 1.8 ton RS-CA-90 41.3 7.00% ㅿ = 2.7 ton RS-CA-45S 41.3 7.00% ㅿ = 2.7 ton RS-CA-45L 47.6 23.3% ㅿ = 9.0 ton

3.1 Load Specimen Load Displacement

As shown in the graph above, the reinforcing ability of the chemical anchor was judged to have a difference in reinforcing effect according to the insertion angle and depth. .

This is because the shear failure is a brittle failure when reinforced at right angles and the reinforcement effect is deteriorated due to the sudden slippage between the chemical anchor and concrete.

 Also, the longer the insertion depth, the better the effect. The longer the installation depth of the anchor, the greater the reinforcement effect.

(a) CONT-S

(b) RS-ST

(b) RS-ST

(c) RS-CA-90

(d) RS-CA-45S

(e) RS-CA-45L

                          [Final Destruction Aspects]

3.2 Evaluation of each specimen stiffness

Stiffness is generally defined as the slope of the load-deflection curve.

K = Ρ / δ (Ρ: ultimate load (ton), δ: displacement at extreme load (mm))

As shown in the graph above, the test specimens of RS-CA-45S, RS-CA-45L, and RS-CA-90 with flexural stiffeners showed greater stiffness than the RS-ST specimens without flexural stiffeners.

This is due to the difference in cross-section stiffness of the stiffener, which means that the stiffness varies depending on the existence of the stiffener, regardless of the shear stiffening method. At the same time, reinforcement seems to be effective.

4. Conclusion

It is judged that the shear reinforcement of the slab is sufficiently possible through this experiment, and the following method can be expected to maximize the reinforcement method.

1) Reinforce the anchor in the direction perpendicular to the sinusoidal crack of the shear crack.

2) Insertion length is considered to be more effective as long as possible, but in reality, it is appropriate to calculate the reinforcement length in consideration of the destruction of the waterproof layer on the upper surface.

3) For flexural reinforcement, reinforcement effect can be obtained only by flexural reinforcement method separate from shear reinforcement.

A: Anchor C: Concrete Structure
M: Mortar R: Stiffener

Claims (7)

delete delete delete Arranging the deteriorated surface of the concrete structure (C); Repairing a cross section using mortar on the cleaned surface; Fixing the reinforcing material (R) to a site where the bending stress of the concrete structure (C) acts; Comprising the step of installing the anchor (A) in the shear stress acting portion of the concrete structure (C), the reinforcement (R) is made of any one or at least two or more materials of metal or FRP, the anchor ( A) is made of any one metal or FRP or at least two or more materials, and consists of a chemical anchor (mechanical anchor) or a mechanical anchor (mechanical anchor), the insertion angle of the anchor (A) is the sinusoidal crack direction And the insertion depth of the anchor (A) is at least d / 2 (d: effective depth (distance from the center of the longitudinal tension bar to the concrete compression edge)), up to the maximum tension bar. , The insertion gap of the anchor (A) is a maximum d or less, and the insertion diameter of the anchor (A) is the diameter of the change value according to the characteristics of the concrete structure, the simultaneous reinforcement and bending method of the concrete structure. delete delete delete

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