JP2024015866A - Structure having crack-inducing structure and construction method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure having a high quality crack-inducing structure.

SOLUTION: A structure having a crack-inducing structure with a main body formed of any one of concrete, mortar, and grout, and a columnar hollow part is formed inside the main body. A construction method of a structure comprises, as an embodiment, the steps of: installing a columnar or cylindrical member 21; installing a form outside the member 21; placing concrete inside the form to form a body part, and removing the member to form a hollow part 20.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a structure having a crack-inducing structure and a construction method thereof.

A structure is known in which a crack-inducing structure is formed by burying reinforcing bars inside the main body (Patent Document 1).

Japanese Patent Application Publication No. 2007-231573 Japanese Patent Application Publication No. 2011-174258

When reinforcing bars are used to induce cracks, the reinforcing bars come into contact with air and moisture through the cracks, which can cause rust stains on the exterior of the structure and corrosion of the reinforcing bars.

In one aspect, the present invention provides a structure having a crack-inducing structure, including a main body formed of concrete, mortar, or grout, and a columnar hollow part is formed inside the main body. I will provide a.

In one embodiment, the present invention includes a step of installing a columnar or cylindrical member, a step of installing a formwork outside the member, and a step of pouring concrete inside the formwork to form the main body. Provided is a method for constructing a structure, comprising a step of forming the member and a step of removing the member to form a hollow portion.

According to the present invention, a structure having a high quality crack-inducing structure can be provided.

(a) A cross-sectional view of the earthquake-resistant wall according to the first embodiment, (b) a cross-sectional view of the earthquake-resistant wall according to the second embodiment, and (c) a perspective view of the earthquake-resistant wall. This is the construction flow for earthquake-resistant walls. It is a figure which shows the construction procedure of a seismic wall, and shows (a) a reinforcement process, and (b) a cylindrical member installation process. It is a figure which shows the construction procedure of a seismic wall, and shows (a) a formwork erection process, and (b) a cylindrical member pulling out process. It is a diagram showing the situation when installing a seismic wall in an existing structure, and shows (a) a frame made of columns and beams in an existing structure, and (b) a situation in which a seismic wall is subsequently installed on an existing structure. FIG. 7 is an explanatory diagram regarding the formation of a hollow portion according to modification example (2), and includes (a) a diagram showing a tube used for forming the hollow part, and (b) a diagram showing a situation in which the tube is pulled out from a seismic wall. It is a figure showing the test specimen used for an experiment, and (a) test specimen A and (b) test specimen B are shown. It is a reinforcement diagram of test specimen A. It is a reinforcement diagram of test specimen B. It is a table showing the material properties of the test specimen, showing (a) the concrete properties of the shear wall, (b) the concrete properties of the beam, and (c) the mechanical properties of the reinforcing bars. (a) A diagram showing a crack that occurred in test specimen A, and (b) a crack that occurred in test specimen B. It is a graph showing the force history applied to each test piece. It is a graph showing the relationship between the member angle and the load in (a) test piece A and (b) test piece B obtained by experiment.

<First embodiment>
A shear wall 10, which is a first embodiment of the structure of the present invention, will be described below. The earthquake-resistant wall 10 shown in FIG. 1(a) is a reinforced concrete wall. Below, as shown in FIG. 1 etc., the width direction, height direction (or up and down direction), and thickness direction shall be defined based on the shape of the seismic wall 10 and used for explanation.

The earthquake-resistant wall 10 includes a concrete portion 40 and a reinforcement 30 composed of vertical reinforcements 30a and horizontal reinforcements 30b. The vertical reinforcements 30a and the horizontal reinforcements 30b are arranged in a lattice shape at a predetermined pitch, and are buried in the concrete portion 40. In this embodiment, the lattice of the vertical reinforcements 30a and the horizontal reinforcements 30b is formed in two parallel rows at intervals in the wall thickness direction, forming a so-called double reinforcement arrangement.

A decorative joint 14 extending in the height direction (vertical direction) is provided on the side surface of the seismic wall 10. This decorative joint 14 has a depth of about 1/10 of the wall thickness, and is formed on either or both sides of the seismic wall 10. Further, the decorative joints 14 are provided at appropriate intervals in the width direction of the wall.

The concrete portion 40 forms additional pours 41 that form the decorative joints 14. The thickness of the additional shot 41 is equal to the depth (dimension in the wall thickness direction) of the decorative joint 14. In other words, the cutout of the additional cutout 41 forms the decorative joint 14.

A hollow portion 20 is formed near the decorative joint 14 and between the double reinforcing bars 30 in the thickness direction. The hollow portion 20 is a portion formed by a defect in the concrete portion 40, and forms a columnar space inside the concrete portion 40. The hollow portion 20 extends in the height direction and has the same length as the vertical length of the seismic wall 10. The vertical stripes 30a and the hollow portion 20 are arranged so that they do not coincide with each other. The diameter of the hollow portion 20 is arbitrarily set depending on the conditions, but it is desirable to set it to 1/4 or more and 1/3 or less of the wall thickness. For example, when the wall thickness of the seismic wall 10 (excluding the additional reinforcement 41) is 200 mm, the depth of each decorative joint 14 can be 20 mm, and the diameter of the hollow part 20 can be 50 mm.

Note that the hollow portion 20 is not limited to a cylindrical shape, but may have an elliptical or polygonal cross section.

When the concrete portion 40 shrinks due to dryness or temperature, cracks 12 are generated that extend in the height direction along the hollow portion 20, as shown in each figure in FIG. The earthquake-resistant wall 10 thus forms a structure that concentrates the strain in the concrete portion 40 near the hollow portion 20 and induces cracks.

The transverse reinforcement 30b arranged in the vicinity of the hollow portion 20 may be subjected to rust prevention treatment such as applying a rust preventive agent or wrapping it with stainless steel material in an area sufficiently wider than the width of the decorative joint 14. .

In this case, since the horizontal reinforcement 30b arranged in the decorative joint 14 portion that induces the crack 12 is rust-proofed, even if it comes into contact with the outside air and moisture through the crack 12, the horizontal reinforcement 30b will not corrode or rust. Prevented. Furthermore, even if water seeps out from the cracks 12, it does not contain iron, so it does not turn into rust, and the wall surface is prevented from discoloring and spoiling its aesthetic appearance.

Furthermore, the decorative joint 14 is filled with a sealing member 16 made of resin. A specific example of the material for the seal member 16 is non-vulcanized butyl rubber. The sealing member 16 can prevent the cracks 12 from being exposed to the outside, and when the seismic wall 10 is used as an exterior wall, it prevents air, rainwater, etc. from entering the seismic wall 10 through the cracks 12. When used as an inner wall, moisture caused by moisture or condensation is prevented from seeping out through cracks. In this way, neutralization of the concrete portion 40 and rusting of the reinforcement 30 are prevented, and the aesthetic appearance of the wall surface can be maintained.

Furthermore, when the sealing member 16 is made of non-vulcanized butyl rubber, due to its characteristics, it is chemically reactively bonded to fresh concrete and reliably joined, and even if the concrete portion 40 shrinks due to temperature changes or drying, its elasticity Therefore, the cracks 12 can be reliably closed and water stopped without deforming and peeling off as the concrete part 40 deforms.

The decorative joint 14 similarly forms a structure that induces cracks. Since the cracks 12 generated in the decorative joints 14 are covered by the sealing member 16, outside air and moisture are prevented from entering the cracks 12. By preventing outside air and moisture from entering into the cracks 12, neutralization of the concrete portion 40 and corrosion of the reinforcing bars 30 are prevented. Moreover, since the sealing member 16 covers the cracks 12, the beauty of the seismic wall 10 is maintained.

<Second embodiment>
A seismic wall 11 according to a second embodiment will be explained. As shown in FIG. 1(b), the earthquake-resistant wall 11 according to the second embodiment further includes a cylindrical member 21 made of a material different from concrete, and the hollow portion 20 is formed by the cylindrical member 21. Ru. In addition, below, the same reference number is attached|subjected to the same member as 1st Embodiment, and description is abbreviate|omitted.

The cylindrical member 21 is embedded in the concrete part 40 and extends vertically so as to surround the hollow part 20. In other words, the hollow portion 20 is formed inside the cylindrical member 21 and defined by the inner peripheral surface of the cylindrical member 21 .

In FIG. 1B, the cylindrical member 21 is formed into a hollow cylindrical shape, but may be formed into a shape other than a cylinder, such as an elliptical cylinder shape or a rectangular cylinder shape.

Various materials can be used for the cylindrical member 21. As an example, a pipe made of vinyl chloride can be used as the cylindrical member 21. When vinyl chloride is used as the material for the cylindrical member 21, adhesion to concrete is prevented.

Note that a release agent may be applied to the outer peripheral surface of the cylindrical member 21. In this case, peeling from the concrete material is promoted. Since the concrete portion 40 easily peels off from the cylindrical member 21, cracks 12 are likely to occur.

Note that when a vinyl chloride pipe is used as the cylindrical member 21, the bonding strength between the vinyl chloride and the concrete part 40 is low, so it is expected that the cylindrical member 21 will peel off from the concrete part 40 without using a release agent. can.

<Construction>
The construction procedure for the shear walls 10 and 11 will be explained using the construction flow shown in FIG. 2.

(Step S1) The worker arranges the reinforcement by assembling the vertical reinforcements 30a and the horizontal reinforcements 30b in a grid pattern (FIG. 3(a)).

(Step S2) After the reinforcement arrangement or in parallel with the reinforcement work, the operator installs the cylindrical member 21 (FIG. 3(b)). The cylindrical member 21 is used to form the hollow part 20. The surface of the cylindrical member 21 may be coated with a release agent.

(Step S3) After reinforcing, as shown in FIG. 4(a), formwork 50 is erected at positions corresponding to both side surfaces of the seismic walls 10 and 11. A joint rod 51 extending in the height direction is fixed to the surface of the formwork 50. The outer shape of the joint bar 51 corresponds to the shape of the decorative joint 14. Incidentally, the erection of the formwork 50 may be performed in parallel with steps S1 and S2, or some or more of steps S1 to S3 may overlap or the order may be reversed.

(Step S4) After completing the erection of the formwork, the worker pours fresh concrete into the formwork, and then cures the concrete until it hardens.

(Step S5) After the poured concrete hardens and loses fluidity to some extent, the operator pulls out the cylindrical member 21 from inside the concrete and removes it (FIG. 4(b)). Furthermore, the formwork 50 and the joint rods 51 are removed from the molds, and the worker completes the construction of the shear wall 10.

A decorative joint 14 is formed on the surface of the seismic wall 10 according to the outer shape of the joint bar 51. The decorative joint 14 is filled with a sealing member 16 as required. Further, a hollow portion 20 is formed in the portion where the cylindrical member 21 was installed.

In addition, it is also possible to harden the concrete without removing the cylindrical member 21 after pouring the concrete. In this case, a shear wall 11 having a crack-inducing structure is formed. As described above, the cylindrical member 21 is embedded inside the seismic wall 11 as shown in FIG. 1(b), and the hollow portion 20 is formed inside the cylindrical member 21.

<Modified example>
(1) Shear walls made of grout The shear walls 10 and 11 may be made of concrete such as mortar or grout instead of concrete. In particular, grout shrinks more than regular concrete. Therefore, when the shear walls 10 and 11 are made of grout, it can be said that the hollow portion 20 is highly effective in inducing cracks. Note that in this specification, concrete refers not only to concrete but also to materials containing cement, such as grout and mortar.

The grouted shear walls 10, 11 can be used to reinforce existing structures. As an example, as shown in FIG. 5(a), it is conceivable to form seismic walls 10 and 11 in a frame formed by existing columns CN and beams BM. In this case, the outer peripheral portions of the seismic walls 10 and 11 are fixed to the column CN and the beam BM via anchors and fixing bars (not shown).

When newly providing shear walls 10 and 11 to reinforce an existing structure as shown in FIG. 5(b), it is possible to use concrete construction, but it is preferable to use grout construction. This is because grout does not contain aggregate and fresh grout is easier to manufacture than concrete. Another reason is that there is no need to consider the concrete pump truck, pressure pipe, or bucket conductor during construction.
(2) Formation of Hollow Part When constructing the shear wall 10, the worker uses a substantially cylindrical or another member formed in a substantially cylindrical shape instead of the cylindrical member 21 to form the hollow part 20. Can be used. For example, it is conceivable to form the hollow portion 20 by using the hole forming member described in Patent Document 2 instead of the cylindrical member 21. When such a member is used, the pulling operation (step S5) is easy.

As another example, as shown in FIG. 6(a), it is possible to use a flexible tube 61. The tube 61 is made of a soft plastic material such as vinyl and has a tubular shape, and is hollow inside.

At the time of construction, the tube 61 can be installed in place of the cylindrical member 21 in the above-mentioned "step S2". In this case, before concrete is poured (step S4), the inside of the tube 61 is filled with a fluid such as air or water to form a cylindrical shape. In "Step S5", the fluid is removed from the inside of the tube 61 to deflate it, and the tube 61 can be pulled out from the concrete part 40 as shown in FIG. 6(b).

The use of the tube 61 is particularly suitable when installing the shear wall 10 to reinforce an existing structure ((1) above). This is because the tube 61 has flexibility and can be taken out from a small gap. Specifically, the shear wall 10 can be constructed by pulling out the tube 61 from between the existing structure and the newly installed shear wall 10 (FIG. 6(b)). Note that the gap formed as a path for pulling out the tube 61 can be filled with grout or mortar.
(3) Filler in Hollow Part In the seismic wall 11, the inside of the cylindrical member 21 may be filled with a filler. In this case, grout can be considered as the filling material. Further, a filling member having lower rigidity than concrete, such as a polymer material such as urethane or expanded polystyrene, a nonflammable material such as glass wool, or a resin material such as rubber, may be filled. Further, the hollow portion 20 in the seismic wall 10 may be filled with the above filling member.
(4) Type of Wall In the embodiment described above, an example in which cracks 12 are formed in the seismic walls 10 and 11 is used. The present invention is not limited to this, and the hollow portion 20 may be formed in another type of wall such as a partition wall or a wing wall to induce cracks 12. Note that the hollow portion 20 may be used not only for walls but also for horizontal members such as floors and eaves.
(5) Decorative joints Decorative joints 14 do not need to be formed on the seismic walls 10 and 11. The effect of inducing cracks 12 can be sufficiently obtained by the hollow portion 20 alone. The decorative joint 14 may be provided only on one side of the seismic walls 10 and 11 instead of on both sides. Further, the decorative joint 14 does not necessarily have to be filled with the sealing member 16.

<Experiment>
Regarding the shear wall 10 having the above configuration, an experiment was conducted to measure performance such as shear strength. As shown in FIG. 7, the test specimens used in the experiment were two reinforced concrete construction specimens A and B. The test specimen A has a general earthquake-resistant wall A1 that does not have a hollow part. The test body B has a seismic wall B1 having a hollow portion 20B extending in the height direction inside. The specimens A and B each have columns A2 and B2 and beams A3 and B3, and form a rectangular frame surrounding the seismic walls A1 and B1.

The dimensions of the seismic walls A1 and B1 were 1800 mm (millimeter) in the width direction and 800 mm in height, as shown in FIGS. 8 and 9. The thickness of both seismic walls A1 and B1 is 60 mm. The reinforcement of the seismic walls A1 and B1 was double reinforcement, with D4 reinforcing bars arranged in a lattice pattern at a pitch of 110 mm. The wall reinforcement ratio is 0.4%.

The outer diameter of the hollow portions 20B was 18 mm, and they were provided at two locations on the earthquake-resistant wall B1 (FIG. 7(b)). The physical properties of the materials used are as shown in FIG.

Figure 11 shows the cracks that occurred in test specimens A and B. In earthquake-resistant wall A1, cracks due to drying shrinkage occurred in two places at the base that divides the wall board into three equal parts (Figure 11(a)). On the other hand, in the test specimen B having the hollow portions 20B, cracks due to drying shrinkage occurred along the two hollow portions 20B in the central portion (FIG. 11(b)). It can be seen that the hollow portion 20B induces cracks in the wall board as intended.

For these test specimens A and B, alternating positive and negative loading was performed by applying horizontal force to the upper beams A3 and B3, as shown by arrows in FIGS. 7(a) and (b). The history of loads applied to test specimens A and B is shown in FIG.

As shown in FIGS. 13(a) and 13(b), regarding the relationship between the load and the member angle in test specimens A and B, there is no significant difference in the shape of the graph and the maximum yield strength. The maximum yield strength of test specimens A and B was 833 kN (kilonewtons) and 813 kN, respectively. It is considered that the hollow portion 20B has little or no influence on the performance of the seismic wall B1.

<Effect>
In each of the embodiments and modifications described above, the following aspects are disclosed.

(Aspect 1) The shear walls 10 and 11, which are an example of a structure, include a concrete part 40 (corresponding to the main body part) formed of concrete, and a columnar hollow part 20 is formed inside the concrete part 40. be done.

The above configuration forms a structure in which strain is concentrated near the hollow portion 20 and cracks are induced. By intensively generating cracks in the vicinity of the hollow part 20, cracks are not generated in parts other than the vicinity of the hollow part 20, and the beauty and earthquake resistance of the seismic walls 10 and 11 are maintained.

(Aspect 2) In aspect 1, the hollow portion 20 is formed in a cylindrical shape.

In the above configuration, the hollow portion 20 can be formed using, for example, a member having a circular tube shape or a cylindrical shape, so that construction is easy. By forming the hollow part 20 into a cylindrical shape, the strain is not concentrated at a specific location around the hollow part 20, but is evenly distributed in the vicinity of the hollow part 20. This prevents a situation in which the direction of the crack 12 induced in the hollow portion 20 is biased or only the width of a specific crack 12 increases.

(Aspect 3) In Aspect 1 or 2, a decorative joint 14 extending in the same direction as the hollow part 20 is further formed on the surface of the concrete part 40 in the vicinity of the hollow part 20.

By forming the decorative joint 14 in the vicinity of the hollow portion 20, cracks can be easily induced in the vicinity of the decorative joint 14. By covering the decorative joint 14 with a sealant, treatments such as covering cracks become easier. Furthermore, the earthquake resistance and aesthetic appearance of the earthquake-resistant walls 10 and 11 can be maintained.

(Aspect 4) In any one of aspects 1 to 3, the hollow portions 20 are formed at a plurality of equally spaced locations in the earthquake walls 10 and 11.

By providing the hollow portions 20 at equal intervals, cracks can be induced in the vicinity of the hollow portions 20.

(Aspect 5) In any one of aspects 1 to 4, the earthquake-resistant wall 11 further includes a cylindrical member 21 provided inside the concrete portion 40, and the inner peripheral portion of the cylindrical member 21 defines the hollow portion 20. do.

By using the cylindrical member 21, the hollow portion 20 can be easily formed. Moreover, since there is no need to pull out the cylindrical member 21 from the earthquake-resistant wall 11 during construction, construction is easy.

(Aspect 6) In any one of aspects 1 to 5, the hollow portion 20 is filled with a filling member having lower rigidity than concrete.

By using the filling member, construction of the hollow portion 20 becomes easy.

(Aspect 7) In the above configuration and modification, the step S2 of installing a columnar or cylindrical member (the cylindrical member 21, the tube 61), the step S3 of installing the formwork 50 outside the member, and the step S3 of installing the formwork 50 outside the member, A pouring step S4 of pouring concrete to form the concrete portion 40, and a step S5 of forming the hollow portion 20 by removing members such as the tube 61 or the cylindrical member 21 from the concrete portion 40 ( Disclosed is a method for constructing a shear wall 10, which includes a removal step).

(Aspect 8) In aspect 7, the columnar or cylindrical member is formed of a flexible tube 61. Before the casting step S4, a step of filling the tube 61 with fluid is performed. In addition, in the removal process of step S5, after removing the fluid from the tube 61, the tube 61 is removed from the concrete part 40, and the hollow part 20 is formed in the concrete part 40.

With the above configuration, it is possible to easily construct the seismic wall 10 having the hollow portion 20. Furthermore, with the above configuration, the hollow portion 20 can be formed without burying any members, and a structure having a crack-inducing structure can be constructed. In particular, when the hollow portion is formed using the tube 61, construction becomes easier when constructing the earthquake-resistant wall 10 or the like in an existing structure.

10, 11 Earthquake-resistant wall 20 Hollow part 21 Cylindrical member 61 Tube 12 Crack 14 Decorative joint 16 Seal member

Claims (8)

Equipped with a main body formed of concrete, mortar, or grout,
A columnar hollow part is formed inside the main body part.
Structures with crack-inducing structures. The hollow part is formed in a cylindrical shape,
A structure according to claim 1. A joint extending in the same direction as the hollow portion is further formed on the surface of the main body portion in the vicinity of the hollow portion.
A structure according to claim 1 or 2. The hollow portion is formed at a plurality of locations at intervals in the main body portion,
A structure according to claim 1 or 2. further comprising a cylindrical member provided inside the main body,
an inner peripheral portion of the cylindrical member defines the hollow portion;
A structure according to claim 1 or 2. Further comprising a filling member having lower rigidity than the concrete, which is filled in the hollow part.
A structure according to claim 1 or 2. a step of installing a columnar or cylindrical member;
installing a formwork outside the member;
a pouring step of pouring concrete inside the formwork to form a main body;
a removing step of removing the member from the main body to form a hollow part in the main body;
methods of constructing structures, including The member is formed of a flexible tube,
Further comprising a step of filling the member with a fluid before the casting step,
In the removing step, the fluid is removed from the member and then the member is removed from the main body.
The construction method according to claim 7.

Images