JP2000336945A - Construction method for non-reinforced and non-anchor earthquake-resistant reinforced wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply construct an earthquake-resistant reinforced wall having high tenacity by using a high-tenacity FRC material (a short-fiber reinforced cement composite material). SOLUTION: When an earthquake resisting wall 10 is to be extended at an opening 7 in the frame of a reinforced concrete-constructed existing column 2 and an existing beam 3, form at only in one side is erected under the existing beam 3, short fibers are mixed towards the forms and concrete and mortar are mixed, a composite material having improved tensile and being strength and tenacity is manufactured by three-dimensional random blending of the fibers, and high-tenacity FRC material (a short-fiber reinforced cement composite material) 12 in which tensile strain exceeds 1% is sprayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a non-reinforced and non-anchored seismic reinforced wall using a high-toughness fiber-reinforced cement composite material.

[0002]

2. Description of the Related Art To improve the seismic performance of a structure, FIG.
It is common practice to add a reinforced concrete earthquake-resistant wall 1 as shown in FIG. Fig. 7 shows a case of a reinforced concrete building.
Is an existing reinforced concrete beam, and the reinforced concrete earthquake-resistant wall 1 is disposed at an opening in the frame of the existing column 2 and the existing beam 3.

[0005] However, such an existing earthquake-resistant wall made of the conventional reinforced concrete earthquake-resistant wall 1 requires many steps as follows.

[0004] By using a number of post-installed anchors such as arranging anchor bars 4 or double reinforcing bars 5,
It is necessary to ensure the integrity of the existing pillar 2 and the existing members such as the existing beam 3. In addition, a series of operations such as formwork assembly, reinforcing bar arrangement, and concrete placement are necessary for the construction of the reinforced concrete earthquake-resistant wall 1 itself.

On the other hand, a composite material (short fiber reinforced cement composite material, FRC) having improved tensile / bending strength and toughness by mixing short fibers with kneading concrete and mortar and randomly mixing the fibers. ) Is popular.

Japanese Unexamined Patent Application Publication No. 10-152927 proposes a method of omitting post-installation anchors and rebar arrangement work using a cotter and sprayed FRC bonded to a peripheral frame without driving in post-installation anchors. .

As shown in FIG. 8, when constructing the earthquake-resistant wall 6, first, a large number of block-shaped cotters 8 are arranged at predetermined intervals on the surfaces of the existing columns 2 and the existing beams 3 on the opening 7 side and bonded. . Next, a fiber reinforced mortar 9 is sprayed on the opening 7 so as to be included in the peripheral portion of the cotter 8 to construct the earthquake-resistant wall 6.

[0008]

However, Japanese Patent Application Laid-Open Publication No.
According to Japanese Patent Application Laid-Open No. 0-152927, 1) the step of bonding the cotter 8 to the peripheral frame still remains.
2) Since the conventional fiber-reinforced mortar 9 (sprayed FRC) is used, if a shear crack occurs in the unreinforced earthquake-resistant wall 6 when a horizontal force is applied, the crack propagates as it is, resulting in a large opening displacement, and abrupt opening displacement occurs. Is expected to lose proof stress and exhibit brittle behavior.

An object of the present invention is to overcome the disadvantages of the prior art and to provide a high toughness FRC material (short fiber reinforced cement composite material).
An object of the present invention is to provide a method of constructing a non-reinforced, non-anchored seismic retrofitting wall that can easily construct a high-toughness seismic retrofitting wall by using.

[0010] In order to achieve the above object, the present invention provides a first method.
Then, only one formwork is erected under the beam, and a high toughness FRC material (short fiber reinforced cement composite material) is sprayed toward the formwork. Secondly, two formwork sides are constructed,
Third, a high-toughness FRC material (short fiber reinforced cement composite material) is poured into the opening. Third, a PCa plate (precast concrete plate) manufactured at the factory is inserted into the opening of the existing frame and temporarily fixed. Press-fitting a high toughness FRC material (short fiber reinforced cement composite material) between the plates and between the PCa plates at the site;
The gist of the present invention is to stack blocks formed of a high toughness FRC material (short fiber reinforced cement composite material).

Sixth, the high toughness FRC material (short fiber reinforced cement composite material) is a crack-dispersed type exhibiting a tensile strain of 1% or more in a tensile test of a hardened material on an age of 28 days. The PVA short fiber of [F1] has a water cement ratio of 40% or more and a sand cement ratio (S / C) of 1.0.
For the following (including 0) formula matrix, more than 1.5 3v
o1. The gist of the present invention is that it is a three-dimensionally random blended material with a blending amount of%. [F1] • Fiber diameter 40 to 50 μm • Fiber length 5 to 20 mm • Fiber strength 1000 MPa to less than 1500 MPa • Apparent fiber strength 700 MPa to less than 1000 MPa

Seventh, the high toughness FRC material (short fiber reinforced cement composite material) is a crack-dispersed type exhibiting a tensile strain of 1% or more in a tensile test of a hardened material on the age of 28, and has the following [F2 ] PVA short fiber of water-cement ratio 30
% Or more and the sand-cement ratio (S / C) is 1.0 or less (0
Is included in the formulation matrix of 1 to 3 vo1. The gist of the present invention is that it is a three-dimensionally random blended material with a blending amount of%. [F2]-Fiber diameter 50 µm or less-Fiber length 5 to 20 mm-Fiber strength 1500 MPa to 2400 MPa or less-Apparent fiber strength 1000 MPa to 1800 MPa or less

According to the first aspect of the present invention, high toughness F
When RC material (short fiber reinforced cement composite material) is post-cast on existing concrete, the behavior of the interface is rich in toughness and withstands high in-plane shearing force. Great improvement is expected compared to the case of casting. Therefore, it is possible to delay the sliding failure at the boundary between the existing building and the additional earthquake-resistant wall, and to endure high shearing force.

[0014] By using a high toughness FRC material (short fiber reinforced cement composite material), it is possible to provide a shear-resistant wall exhibiting a tough behavior. High toughness FRC material (short fiber reinforced cement composite material) not only has tensile behavior,
The compression behavior is also greatly improved in compression behavior as compared with concrete, and in combination with high tensile strain capability, it is possible to withstand very large shear deformation. Therefore, the seismic retrofit wall formed by the present invention exhibits a behavior that is very rich in toughness as compared with general RC.

[0015] Therefore, by setting up only one formwork under the beam and spraying a high-toughness FRC material (short fiber reinforced cement composite material) on the formwork, the earthquake-resistant reinforcement wall can be formed very easily and quickly. Can be formed.

According to the second aspect of the present invention, similarly to the above-described operation, two front and back molds are constructed, and a high toughness FR is applied thereto.
By injecting the C material (short fiber reinforced cement composite material), it is possible to form the earthquake-resistant reinforcing wall very simply and quickly.

According to the third aspect of the present invention, similarly to the above-described operation, after the temporary fixing, a high toughness FRC material (short fiber reinforced cement) is formed on site between the existing frame and the PCa plate and between the PCa plates. By press-fitting the composite material), the earthquake-resistant reinforcing wall can be formed very easily and quickly.

According to the fourth aspect of the present invention, similar to the above-described operation, the seismic strengthening wall can be very simply and quickly formed by stacking blocks formed of a high toughness FRC material (short fiber reinforced cement composite material). Can be formed.

According to the fifth and sixth aspects of the present invention, an inexpensive general-purpose PVA fiber (the apparent fiber strength in a matrix is 1/2 to that of a high-performance polyethylene fiber).
A high toughness FRC material (short fiber reinforced cement composite material) can be realized by using only about 1/3).

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partially cutaway front view showing an embodiment of an additional seismic retrofitting wall constructed by the method of constructing a non-reinforcement non-anchor seismic retrofitting wall of the present invention, and FIG. FIG. 1 is a vertical sectional side view showing a first embodiment of a method of constructing an earthquake-resistant reinforcing wall. In FIG. 1, the same components as those in FIG. 7 showing the conventional example are denoted by the same reference numerals.

That is, in a reinforced concrete building,
When an earthquake-resistant wall 10 is to be added to the opening 7 in the frame between the existing reinforced concrete column 2 and the existing beam 3, only one formwork 11 is erected under the existing beam 3 as shown in FIG. A high toughness FRC material (short fiber reinforced cement composite material) 12 is sprayed to perform the construction.

The mold 11 may be removed from the mold at a later date, or may be buried. In the case of burying, the metal frame is formed in consideration of the adhesion of the high toughness FRC material (short fiber reinforced cement composite material) 12. Use of the body is possible.

The high toughness FRC material (short fiber reinforced cement composite material) 12 is a crack-dispersed type showing a tensile strain of 1% or more in a tensile test of a hardened material on the age of 28,
The PVA short fiber of the following [F1] was added to a blend matrix having a water cement ratio of 40% or more and a sand cement ratio (S / C) of 1.0 or less (including 0) to exceed 1.5 and 3 vol. % Is randomly blended three-dimensionally. [F1] • Fiber diameter 40 to 50 μm • Fiber length 5 to 20 mm • Fiber strength 1000 MPa to less than 1500 MPa • Apparent fiber strength 700 MPa to less than 1000 MPa

Alternatively, the high toughness FRC material (short fiber reinforced cement composite material) 12 is a crack-dispersed type exhibiting a tensile strain of 1% or more in a tensile test of a hardened body on the age of 28, and has the following [F2] Of PVA short fibers in a mixing matrix having a water-cement ratio of 30% or more and a sand-cement ratio (S / C) of 1.0 or less (including 0) is more than 1 vol. %
Is randomly blended three-dimensionally. [F2]-Fiber diameter 50 µm or less-Fiber length 5 to 20 mm-Fiber strength 1500 MPa to 2400 MPa or less-Apparent fiber strength 1000 MPa to 1800 MPa or less

The high toughness FRC material 12 containing the PVA fiber
Has a matrix and fiber friction adhesion strength of 1 to 6 MPa,
The chemical adhesion strength is 40 MPa or less.

Then, in preparing a fiber reinforced cement composite material (FRC material) in which PVA short fibers are randomly mixed in a mortar in a three-dimensional direction, the following formula (5) is used.
Determining completion mental energy J 'and _b, between the matrix fracture toughness J _tip having a relationship of equation _{(l), 3J tip <J} ' a and the formulation of the matrix using a PVA short fiber relationship _b is established which is obtained by And a method for preparing a high toughness FRC material using PVA short fibers. I will provide a.

[0027]

(Equation 1) Where σ _a : acting stress when _a multi-crack occurs δ _a : opening displacement at the center of the crack when _a multi-crack occurs σ _c : bridging stress due to fiber σ _c (δ): relationship between bridging stress σc due to fiber and opening displacement δ δ _peak : Maximum bridging stress δ _peak : Opening displacement corresponding to σ _peak . Here, J _tip is a value that can be controlled by the preparation of the matrix, that is, the water-cement ratio or the sand / cement ratio, and the value can be confirmed by an experiment. For example, Ogishi, Ono: Effect of test factors on fracture toughness of cement paste and mortar, "Concrete Engineering" vol.2
5. No. 2, PP. 113-125.

The high toughness FRC material 12 containing the PVA fiber
Has a tensile strain of 1% or more, preferably 2% or more.
The term "tensile strain" as used herein refers to the amount of strain (%) at the maximum tensile stress value in a stress-strain curve obtained by a tensile test of a cured body having an age of 28 days or more. Actually, tensile strain (%) in a tensile test of a specimen on a material age of 28 days (for example, a specimen having a cross section of 30 mm x 13 mm is subjected to a tensile test in a test section of 80 mm as shown in Examples described later)
Is represented by

The fact that the tensile strain is 1% or more means that
This means that a crack-dispersed fracture phenomenon in which a number of cracks (multi-cracks) occur in a direction substantially perpendicular to the loading direction (stress direction) has occurred. Until now, the FRC material containing PVA fiber itself is known, but its tensile strain is at most about 0.5%, and the FRC material containing PVA fiber which has achieved a tensile strain of 1% or more due to the occurrence of multi-cracks. Sees no example.

For example, in JP-A-5-24897,
Two types of PVA fiber (vinylon fiber) with different diameter and length
A mortar which can be made thicker and has excellent resistance to cracking by blending with a compound is disclosed. However, the flexural toughness is at most 20 times that of the mortar containing no fiber. 5% or less (a tensile strain of about 1
%, The flexural toughness should be about 80 times or more that of the fiber-free one).

The high toughness FRC material 12 containing the PVA fiber
According to Steady Sta, the cause of multi-cracks
In order to realize the te cracking phenomenon (SSC phenomenon) with the PVA fiber, when the properties of the PVA fiber used and the properties of the matrix are well combined, the high toughness of the tensile strain of 1% or more, preferably 2% or more even for the PVA fiber. FRC material 12
Is obtained.

That is, the following PVA short fiber F1 is prepared by mixing a water-cement ratio (W / C × 100) of 40% or more and a sand-cement ratio (S / C) of 1.0 or less (including 0). In addition, when it is dispersed and blended in a three-dimensional direction at a blending amount of more than 1.5 to 3 vol.% (Referred to as blending),
The PVA fiber F2 was converted to a water-cement ratio (W / C × 10
0) is 30% or more and the sand-cement ratio (S / C) is 1.0 or less (including 0). In such a case (called “combination”), a crack-dispersed high toughness FRC material is obtained.

"Apparent fiber strength" in F1 and F2
Is the strength at which the PVA fiber breaks in the actual FRC material, and can be measured by performing a break test on the fiber in the actual FRC material.

In the formulation using F1, if the water-cement ratio of the matrix is less than 40%, the elastic modulus and fracture toughness of the matrix are increased for this fiber, so that multi-cracks do not occur and tensile strain of 1% or more occurs. do not do.
On the other hand, if the sand-cement ratio exceeds 1.0, the elastic modulus and fracture toughness of the matrix are increased for this fiber, so that multi-cracks do not occur and no tensile strain of 1% or more occurs. Therefore, the matrix in the case of using F1 fiber is 40% or more of water cement, preferably 42% or more, more preferably 44% or more, and the sand cement ratio is 1.0%.
Or less, preferably 0.7 or less, more preferably 0.5
The following is assumed. However, even with this blended matrix, if the amount of the F1 fiber is less than 1.5 vol.%, Multicracks do not occur.
l.% need to be more. However, the effect is saturated even if it is added in an excessively large amount.

Even with the matrix and fiber blending amount of this blend, if the length of the F1 fiber is less than 5 mm, multi-cracks do not occur, so it is necessary to use a fiber having a length of 5 mm or more. . However, even if a material longer than 20 mm is used, multicracks do not occur at the above-mentioned amount. Therefore, the length of the F1 fiber is 5 to 20 m.
m, preferably 6 to 20 mm, more preferably 8 to 15 mm.

On the other hand, in the composition using F2, if the water-cement ratio of the matrix is less than 30%, the elastic modulus and fracture toughness of the matrix are increased for this fiber, so that multi-cracks do not occur, and the tensile strain is 1% or more. Does not occur. On the other hand, if the sand-cement ratio exceeds 1.0, the elastic modulus and fracture toughness of the matrix are increased for this fiber, so that no matrix is generated and no tensile strain of 1% or more is generated. Therefore, the matrix in the case of using F2 fiber is 30% or more of water cement, preferably 32% or more, more preferably 35% or more, and the sand cement ratio is 1.0%.
Or less, preferably 0.7 or less, more preferably 0.5
The following is assumed. However, even with this blended matrix, if the amount of F2 fiber is less than 1.0 vol.%, Multicracks are unlikely to occur.
It needs to be more than vol.%. However, the effect is saturated even if it is added in an excessively large amount.

Even with the matrix and fiber blending amount of this blend, if the length of the F2 fiber is less than 5 mm, multi-cracks do not occur, so it is necessary to use a fiber having a length of 5 mm or more. . However, even if a material longer than 20 mm is used, multicracks do not occur at the above-mentioned amount. Therefore, the length of F2 fiber is 5-20m
m, preferably 6 to 18 mm, more preferably 6 to 15 mm.

High toughness FRC material containing PVA fiber 1
2. Since the fracture toughness is improved to a level equivalent to that of metal aluminum (on the order of 100 times that of ordinary concrete), the behavior of the material is hardly influenced by the size of the initial defects that always exist inside the material. Therefore, when the reliability of the material is greatly increased, the safety factor can be reduced when designing the member, and the allowable stress closer to the actual material strength can be obtained.

As a second embodiment, when an earthquake-resistant wall 10 is added to the opening 7 in the frame of the existing column 2 and the existing beam 3 made of reinforced concrete, as shown in FIG.
a, 13b are installed at appropriate intervals, and the formwork 13a,
A high-toughness FRC material (short fiber reinforced cement composite material) 12 is provided between 13b and a connection port 14 is provided at a lower portion of one of the molds, and a press-fit hose 15 is connected to the connection port 14 and press-fitted.

As a third embodiment, as shown in FIG. 4, two molds 13a and 13b are installed at appropriate intervals, and a high toughness FRC material (short fiber reinforcement) is provided between the molds 13a and 13b. When the cement composite material) 12 flows in, the hopper
16 may be formed and poured from here.

In each of the second and third embodiments, the molds 13a and 13b may be made of any material such as a plywood, a metal plate, and a concrete plate. Further, any type of burial or demolding may be used.

As a fourth embodiment, as shown in FIG.
When adding an earthquake-resistant wall 10 to the opening 7 in the frame of the existing reinforced concrete columns 2 and existing beams 3, the PCa
After the slab (precast concrete slab) 17 is set up temporarily in the opening 7 and temporarily fixed, a high-toughness FRC is applied between the existing frame formed by the existing columns 2 and the existing beams 3 and the PCa slab 17 and between the PCa slabs 17 on site. The material (short fiber reinforced cement composite material) 12 is filled. This filling is suitably press-fitted with a hose or the like.

Further, the PCa plate 17 forms irregularities on the outer periphery and performs a cotter-like action.

As a fifth embodiment, as shown in FIG.
When an earthquake-resistant wall 10 is to be added to the opening 7 in the frame of the existing column 2 and the existing beam 3 made of reinforced concrete, a block formed of a high-toughness FRC material (short fiber reinforced cement composite material) 12
Stack 18,

The shape of the block 18 is not particularly limited, and various shapes such as a concrete block shape and a brick shape which are usually used can be considered.

Further, the gap between the existing frame and the block 18 and the gap between the block 18 and the existing column 2 and the existing beam 3 is filled with mortar or a high toughness FRC material (short fiber reinforced cement composite material) 12.

[0047]

As described above, the construction method of the non-reinforced, non-anchored seismic retrofitting wall of the present invention uses a high toughness FRC material (short fiber reinforced cement composite material) to easily provide high toughness. It is possible to construct a seismic reinforcement wall.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of an additional seismic retrofitting wall constructed by a method of constructing a non-reinforcement / anchor-free seismic retrofitting wall of the present invention.

FIG. 2 is a longitudinal sectional side view showing a first embodiment of a method for constructing a non-reinforced / anchor-free earthquake-resistant reinforced wall of the present invention.

FIG. 3 is a longitudinal sectional side view showing a second embodiment of a method for constructing a non-reinforced / anchor-free earthquake-resistant reinforced wall of the present invention.

FIG. 4 is a longitudinal sectional side view showing a third embodiment of a method for constructing a non-reinforced / anchor-free earthquake-resistant reinforced wall of the present invention.

FIG. 5 is a front view showing a fourth embodiment of the method for installing a non-reinforced / anchor-free earthquake-resistant reinforced wall of the present invention.

FIG. 6 is a front view showing a fifth embodiment of a method for constructing a non-reinforced / anchor-free, seismic reinforced wall according to the present invention.

FIG. 7 is a partially cutaway front view showing a conventional example.

FIG. 8 is a partially cutaway front view showing another conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reinforced concrete shear wall 2 ... Existing column 3 ... Existing beam 4 ... Anchor bar 5 ... Reinforcement bar 6 ... Shear wall 7 ... Opening 8 ... Cotter 9 ... Fiber reinforced mortar 10 ... Shear wall 11 ... Formwork 12 ... High toughness FRC Material (short fiber reinforced cement composite material) 13a, 13b ... Form 14 ... Connection port 15 ... Press-fit hose 16 ... Hopper 17 ... PCa version 18 ... Block

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) E04B 2/84 E04B 2/84 K (72) Inventor Masaya Taki 2-9-1-1, Tobita-Kita, Chofu-shi, Tokyo Kashima Construction Co., Ltd. F-term (reference) 2E176 AA01 BB28

Claims (6)

[Claims] 1. A mold having only one side under a beam, mixing short fibers into the concrete and mortar, and randomly mixing the fibers to form a three-dimensional random mixture. High toughness FR with composite material with improved toughness and tensile strain exceeding 1%
A method of constructing a non-reinforced, non-anchored, earthquake-resistant reinforced wall characterized by spraying C material (short fiber reinforced cement composite material). 2. A two-sided formwork is constructed, short fibers are mixed therein, and concrete and mortar are mixed and mixed.
The three-dimensional random blending of these fibers allows for tensile and
A non-reinforced, non-anchored seismic resistant composite material characterized by inflow of a high toughness FRC material (short fiber reinforced cement composite material) that is a composite material with improved bending strength and toughness and a tensile strain exceeding 1%. Construction method of reinforced wall. 3. A factory-made PCa plate (precast concrete plate) is set up in the opening of the existing frame and temporarily fixed, and then short fibers are mixed between the existing frame and the PCa plate and between the PCa plates on site. A high-toughness FRC material (short fiber) with tensile and flexural strength and toughness improved by mixing concrete and mortar and mixing the fibers three-dimensionally at random to increase tensile strain. Reinforced cement composite material), and press-fitting it. 4. A composite material in which short fibers are mixed, concrete and mortar are kneaded and mixed, and the fibers are three-dimensionally random-mixed to improve tensile / bending strength and toughness. A method of constructing a non-reinforced, non-anchored, seismic reinforced wall, characterized by stacking blocks formed of a high toughness FRC material (short fiber reinforced cement composite material). 5. A high-toughness FRC material (short fiber reinforced cement composite material) has a tensile strain of 1 in a tensile test of a hardened body on the age of 28.
% Or less, and PVA short fibers of the following [F1] are used as a preparation matrix having a water cement ratio of 40% or more and a sand cement ratio (S / C) of 1.0 or less (including 0). , More than 1.5 3vo1. The method for constructing a non-reinforced, non-anchored, earthquake-resistant reinforced wall according to any one of claims 1 to 4, wherein the non-reinforced, non-anchored, non-reinforced, non-reinforced, seismic reinforced wall is blended three-dimensionally at a blending amount of 3%. [F1] • Fiber diameter 40 to 50 μm • Fiber length 5 to 20 mm • Fiber strength 1000 MPa to less than 1500 MPa • Apparent fiber strength 700 MPa to less than 1000 MPa 6. A high-toughness FRC material (short fiber reinforced cement composite material) has a tensile strain of 1 in a tensile test of a hardened body on the age of 28.
% Or less, and a PVA short fiber of the following [F2] is used as a preparation matrix having a water cement ratio of 30% or more and a sand cement ratio (S / C) of 1.0 or less (including 0). 1 over 3vo1. The method for constructing a non-reinforced, non-anchored, earthquake-resistant reinforced wall according to any one of claims 1 to 4, wherein the non-reinforced, non-anchored, non-reinforced, non-reinforced, seismic reinforced wall is blended three-dimensionally at a blending amount of 3%. [F2]-Fiber diameter 50 µm or less-Fiber length 5 to 20 mm-Fiber strength 1500 MPa to 2400 MPa or less-Apparent fiber strength 1000 MPa to 1800 MPa or less