JP6295019B2 - Concrete structure - Google Patents

Description

  The present invention relates to a concrete structure.

  When the head of a steel pipe pile is joined to a concrete structure such as an RC beam as in a pier structure, a fixing plate is welded to the outer periphery of the pile head at the joint between the pile head and the concrete structure, A mechanical joint is welded to the fixing plate, and a main reinforcing bar of a concrete structure is joined to the mechanical joint (see, for example, Patent Document 1). Thereby, transmission of the force of the main rebar divided by the pile head is made possible.

JP 2007-2492 A

  When constructing the joint between the pile head and the concrete structure described in Patent Document 1, the work of welding the fixing plate to the outer periphery of the steel pipe pile or the work of welding the mechanical joint to the fixing plate However, there is a demand for reducing the welding work because it takes a lot of time.

  This invention is made | formed in view of the said situation, and it seems that the transmission of the force of the divided main rebar is possible for the concrete structure which the main rebar divided on the boundary of the inclusions, such as a pile head. And reducing the welding work when constructing the concrete structure.

In order to solve the above problems, a concrete structure according to the present invention is a concrete structure in which a main reinforcing bar of an RC structure is divided at an inclusion, and the RC structure, the inclusion, It is formed of a fiber reinforced cementitious composite material provided so as to continuously surround the inclusion and to be joined to the inclusion, and an annular reinforcing bar or steel material around the inclusion Is provided , and the RC structure is joined to the fiber reinforcement, and the RC structure does not have a fiber reinforced portion .

  In the concrete structure, the inclusion may be a pile.

  According to the present invention, a concrete structure in which a main reinforcing bar is divided at the boundary of an inclusion such as a pile head is configured so as to be able to transmit the force of the divided main reinforcing bar, and the concrete structure. The welding work when constructing can be reduced.

It is a plane sectional view (1-1 sectional view of Drawing 2) showing RC beam concerning one embodiment. It is 2-2 sectional drawing in FIG. (A), (B) is a plane sectional view for explaining an operation of RC beam concerning this embodiment. It is a plane sectional view showing the RC structure concerning other embodiments.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a plan sectional view (1-1 sectional view of FIG. 2) showing a reinforced concrete beam (hereinafter referred to as RC beam) 10 according to an embodiment, and FIG. 2 is a section 2-2 of FIG. FIG. As shown in these drawings, the RC beam 10 according to the present embodiment is a beam that forms, for example, a pile-type pier, and the head of the steel pipe pile 1 is embedded in the middle portion in the longitudinal direction. .

  The RC beam 10 includes a plurality of upper and lower main reinforcing bars 12 and 14. The upper main reinforcing bar 12 is arranged to pass through the upper side of the head of the steel pipe pile 1 (see FIG. 2). On the other hand, the lower main reinforcing bar 14 is arranged at the height of the head of the steel pipe pile 1 and is divided at the steel pipe pile 1 as a boundary. The RC beam 10 is provided with a shear reinforcing bar 15.

  A fiber reinforced portion 11 formed of a fiber reinforced cementitious composite material is provided around the steel pipe pile 1 at a joint portion between the RC beam 10 and the head portion of the steel pipe pile 1. The fiber reinforcing part 11 is formed at the height of the main reinforcing bar 14, and the end of the main reinforcing bar 14 is embedded. Here, a mechanical fixing bracket 16 is coupled to an end portion of the main reinforcing bar 14, and the end portion is fixed to the fiber reinforcing portion 11.

  As the fiber reinforced cementitious composite material used to form the fiber reinforced portion 11 in the present embodiment, for example, those described in JP2011-42534A can be used. Specifically, cement, Silica fume, water, water reducing agent, fine aggregate and high tension fiber are contained as necessary components.

As for the mineral composition of cement, the amount of C ₃ S is 40.0 to 75.0% by mass and the amount of C ₃ A is less than 2.7% by mass. The amount of C ₃ S in the cement is preferably 45.0 to 73.0% by mass, more preferably 48.0 to 70.0% by mass, and the amount of C ₃ A in the cement is preferably 2.3% by mass. Is less than. If the C ₃ S amount of the cement is less than 40.0% by mass, the compressive strength and tensile strength tend to be low, and if it exceeds 75.0% by mass, the cement itself tends to be difficult to fire. Further, when the amount of C ₃ A of the cement is 2.7% by mass or more, the tensile strength is lowered. The lower limit of the C ₃ A content of the cement is not particularly limited, but is about 0.1% by mass.

Further, the C ₂ S amount of the cement is preferably 9.5 to 40.0% by mass, more preferably 14.0 to 35.0% by mass, and the C ₄ AF amount of the cement is preferably 9.0. It is -18.0 mass%, More preferably, it is 10.0-15.0 mass%.

  If it is the range of the mineral composition of the above cements, the high toughness of a cement-type composition, high compressive strength, high tensile strength, and high fluidity | liquidity can be ensured.

  The cement particle size is such that the 45 μm sieve residue has an upper limit of less than 8.0% by mass, preferably 7.0% by mass or less, more preferably 6.0% by mass or less, and a lower limit of 0%. 0.0 mass%, preferably 1.0 mass% or more, more preferably 2.0 mass% or more. When the particle size of the cement is within this range, high tensile strength can be secured, and a cement slurry prepared using this cement has an appropriate viscosity, so that high-tensile fibers are sufficiently dispersed.

The brane specific surface area of the cement is preferably 2500 to 4800 cm ² / g, more preferably 2800 to 4000 cm ² / g, and still more preferably 3000 to 3600 cm ² / g. When the brane specific surface area of the cement is less than 2500 cm ² / g, the strength of the cementitious composition tends to be low, and when it exceeds 4800 cm ² / g, the fluidity at a low water cement ratio tends to decrease.

  In manufacturing the cement in the present embodiment, it is not necessary to perform an operation different from that of normal cement. The cement is changed according to the target mineral composition such as limestone, silica, slag, coal ash, construction generated soil, blast furnace dust, etc., fired in the actual kiln, gypsum added to the obtained clinker And can be manufactured by pulverizing to a predetermined particle size. A general NSP kiln, SP kiln, or the like can be used for the kiln to be fired, and a general pulverizer such as a ball mill can be used for pulverization. Moreover, 2 or more types of cement can also be mixed as needed.

Silica fume is a by-product obtained by collecting dust in the exhaust gas generated when producing metal silicon, ferrosilicon, fused zirconia, etc., and the main component is amorphous SiO dissolved in an alkaline solution. ₂ . The average particle diameter of the silica fume is preferably 0.05 to 2.0 μm, more preferably 0.10 to 1.5 μm, and still more preferably 0.18 to 0.28 μm. By using such silica fume, the high toughness, high compressive strength, high tensile strength and high fluidity of the fiber reinforced cementitious composite material can be ensured.

  In the fiber reinforced cementitious composite material in the present embodiment, the content of silica fume with respect to the total amount of cement and silica fume is preferably 3 to 30% by mass, more preferably 5 to 20% by mass, and still more preferably 10 to 18% by mass. %. The content of silica fume with respect to the total amount of cement, silica fume and fine aggregate is preferably 3 to 30% by mass, more preferably 5 to 20% by mass, and still more preferably 10 to 18% by mass.

  As the water reducing agent, lignin-based, naphthalenesulfonic acid-based, aminosulfonic acid-based, polycarboxylic acid-based water reducing agents, high-performance water reducing agents, high-performance AE water reducing agents, and the like can be used. From the viewpoint of ensuring fluidity at a low water cement ratio, it is preferable to use a polycarboxylic acid-based water reducing agent, a high-performance water reducing agent or a high-performance AE water reducing agent as the water reducing agent, and a polycarboxylic acid-based high-performance water reducing agent. It is more preferable to use In the fiber reinforced cementitious composite material in the present embodiment, the water reducing agent is preferably 0.5 to 6.0 parts by mass, more preferably 1.0 to 4.0 with respect to 100 parts by mass of the total amount of cement and silica fume. Part by mass, more preferably 2.5 to 3.5 parts by mass.

  Moreover, in the fiber reinforced cementitious composite material in the present embodiment, it is preferable to use an antifoaming agent together with these water reducing agents. Examples of the antifoaming agent include polyalkylene derivatives, hydrophobic silica, and polyethers. In this case, the antifoaming agent is preferably 0.01 to 2.0 parts by weight, more preferably 0.02 to 1.5 parts by weight, and still more preferably 0.000 parts by weight with respect to 100 parts by weight of the total amount of cement and silica fume. Including 03 to 1.0 parts by mass.

  As fine aggregate, river sand, land sand, sea sand, crushed sand, quartz sand, limestone aggregate, blast furnace slag fine aggregate, ferronickel fine aggregate, copper slag fine aggregate, electric furnace oxidation slag fine aggregate, etc. are used. can do. The fine aggregate in this embodiment contains 15 to 85% by mass, preferably 20 to 70% by mass, more preferably 25 to 45% by mass of a particle group having a particle size of 0.15 mm or less, and a particle having a particle size of 0.075 mm or less. The group is contained 3 to 20% by mass, preferably 5 to 15% by mass. If the content of the fine aggregate is less than 15% by mass, the viscosity of the cement slurry is too low, so that the high-tensile fibers may not be sufficiently dispersed. On the other hand, if the content of fine aggregate exceeds 85% by mass, the amount of fine powder is too high and the viscosity becomes high, and it is necessary to increase the water cement ratio to give a predetermined flow, which may lead to a decrease in strength. is there. In addition, although the adjustment method in particular of a fine particle is not specifically limited, For example, it can prepare by mixing two or more types of fine aggregates from which a particle size differs.

The amount of fine aggregate in the fiber reinforced cementitious composite is preferably 400 to 1000 kg / m ³ , more preferably 430 to 850 kg / m ³ , and still more preferably 500 to 750 kg / m ³ .

Examples of the high-tensile fiber include metal fiber, carbon fiber, aramid fiber, and high-strength polyethylene fiber (for example, “Dyneema” manufactured by Toyobo Co., Ltd.). As the metal fiber, steel fiber, stainless steel fiber, amorphous alloy fiber, or the like can be used. The fiber diameter of the high-tensile fiber is preferably 0.05 to 1.20 mm, more preferably 0.08 to 0.70 mm, and still more preferably 0.10 to 0.35 mm. The fiber length of the high-tensile fiber is preferably 3 to 60 mm, more preferably 5 to 35 mm, and still more preferably 7 to 20 mm. The aspect ratio (fiber length / fiber diameter) of the high-tensile fiber is preferably 40 to 250, more preferably 50 to 200, and still more preferably 80 to 170. The tensile strength of the high strength fiber is preferably 100~10000N / mm ^2, more preferably 500~5000N / mm ^2, more preferably 2000~3000N / mm ^2. The density of high-tensile fibers, preferably from 1 to 20 g / cm ^3, and more preferably 5 to 10 g / cm ^3. By using such high-tensile fibers, high toughness, high compressive strength, high tensile strength, and high fluidity can be imparted to the fiber-reinforced cement composite material.

  Moreover, the fiber-reinforced cementitious composite material in the present embodiment is preferably 0.3 to 4.0% by volume, more preferably 0.5 to 3% of the high-strength fiber by dividing the fiber-reinforced cementitious composite material. 0.0% by volume, more preferably 1.0 to 2.5% by volume. If the high-tensile fiber is less than 0.3% by volume, high toughness that exhibits pseudo-strain hardening may not be obtained. If it exceeds 4.0% by volume, it may be difficult to mix the cement.

  Moreover, the fiber reinforced cementitious composite material in this embodiment can obtain high fire resistance by further including organic fibers. Examples of the organic fiber include polypropylene fiber, polyethylene fiber, and vinylon fiber.

The fineness of the organic fiber is preferably 1.0 to 20 dtex, more preferably 1.5 to 15 dtex, and still more preferably 2.0 to 4.0 dtex. The tensile strength of the organic fiber is preferably 1 to 6 cN / dtex, more preferably 1.5 to 5 cN / dtex, and still more preferably 2 to 4 cN / dtex. The elongation of the organic fiber is preferably 400% or less, more preferably 300% or less, and still more preferably 50 to 200%. The fiber length of the organic fiber is preferably 3 to 30 mm, more preferably 4 to 20 mm, and still more preferably 5 to 15 mm. The density of organic fibers is preferably from 0.8 to 1.5 g / cm ^3, more preferably 0.8~1.3g / cm ^3, more preferably 0.85~0.95g / cm ^3. The aspect ratio (fiber length / fiber diameter) of the organic fiber is preferably 200 to 900, more preferably 300 to 800, and still more preferably 400 to 700.

  By adding organic fibers in such a range, high fire resistance can be secured in addition to high toughness, high compressive strength, high tensile strength and high fluidity of the fiber-reinforced cementitious composite material.

  The fiber reinforced cementitious composite material in the present embodiment is preferably 0.05 to 3% by volume, more preferably 0.1 to 2% by volume, and still more preferably organic fiber in an outer ratio with respect to the fiber reinforced cementitious composite material. Contains 0.3 to 1% by volume. If the organic fiber is less than 0.05% by volume, sufficient fire explosion resistance may not be obtained, and if it exceeds 3% by volume, mixing into the fiber-reinforced cementitious composite material may be difficult.

Moreover, the fiber reinforced cementitious composite material in this embodiment is preferably 10 to 25 parts by mass, more preferably 12 to 20 parts by mass, and still more preferably 13 to 100 parts by mass of the total amount of cement and silica fume. -18 mass parts included. The unit water amount in the fiber reinforced cementitious composite material is preferably 180 to 280 kg / m ³ , more preferably 200 to 270 kg / m ³ , and still more preferably 210 to 260 kg / m ³ .

  In the fiber reinforced cementitious composite material in the present embodiment, an expansion material, a shrinkage reducing agent, a setting accelerator, a setting retarding agent, a thickening agent, glass fiber, a synthetic resin powder, a polymer emulsion, and a polymer dispersion are used as necessary. One or more of these may be added.

  Furthermore, concrete may be prepared by combining a suitable amount of coarse aggregate with the fiber-reinforced cement composite material in the present embodiment. The amount of coarse aggregate and the amount of water may be appropriately changed according to the target compressive strength, toughness, and target slump value. As the coarse aggregate, gravel, crushed stone, limestone aggregate, blast furnace slag coarse aggregate, electric furnace oxidized slag coarse aggregate and the like can be used. Moreover, the coarse aggregate which stays at 85 mass% or more on a 5 mm sieve is more preferable.

  Although the manufacturing method of the fiber reinforced cementitious composite material in this embodiment is not particularly limited, a part or all of materials other than water and water reducing agent are mixed in advance, and then water and water reducing agent are added. After putting in a mixer and kneading to produce cement, the fiber material is further put in a mixer and kneaded. The mixer used for mixing the cement is not particularly limited, and a cement mixer, a biaxial forced mixing mixer, a pan mixer, a grout mixer, and the like can be used.

  3 (A) and 3 (B) are plan views showing the operation of the RC beam 10 according to the present embodiment, and show a portion on one side of the steel pipe pile 1 in the beam length direction. As shown in FIG. 3A, a fiber reinforced portion 11 in which the steel pipe pile 1 penetrates the central portion is formed at the joint portion of the RC beam 10 with the steel pipe pile 1, and the beam in the fiber reinforced portion 11 The ends of the main reinforcing bars 14 are fixed on both sides in the longitudinal direction (left and right direction in the figure). For this reason, when a tensile force acts on the main reinforcing bar 14, as shown in FIG. 3 (B), the portions A on both sides in the longitudinal direction of the beam in the fiber reinforced portion 11 are center portions (positions of end portions of the main reinforcing bar 14). Loads P1 to P4 act on the beam, and the structure is like a beam in which reaction forces R1 and R2 act on both ends (upper and lower ends in the figure). Therefore, bending compressive stress is generated on the steel pipe pile 1 side in the part A, and bending tensile stress is generated on the opposite side.

  In addition, when a tensile force acts on the main reinforcing bar 14, tensile stress in the longitudinal direction of the beam is also generated in the portions B on both sides of the fiber reinforcing portion 11 in the beam width direction (vertical direction in the figure).

  Here, the fiber reinforced portion 11 is formed of a fiber reinforced cementitious composite material, and the portions A on both sides in the longitudinal direction of the beam in the fiber reinforced portion 11 are enhanced in tensile strength in the beam width direction by the high-tensile fiber contained therein. As a result, sufficient tensile strength in the beam width direction is provided. Moreover, the site | part B of the both sides of the beam width direction in the fiber reinforcement part 11 is also fully heightened the tensile strength in the beam longitudinal direction. Therefore, when a tensile force acts on the RC beam 10, the tensile force is transmitted from one main reinforcing bar 14 to the other main reinforcing bar 14 via the fiber reinforcing portion 11.

  As described above, in the RC beam 10 according to the present embodiment, the fiber reinforced portion 11 is formed of the fiber reinforced cementitious composite material around the head of the steel pipe pile 1, and the main reinforcing bar 14 is provided on the fiber reinforced portion 11. By fixing, the force of the main rebar 14 divided by the steel pipe pile 1 can be transmitted. Therefore, the welding work at the time of constructing the joint between the RC beam 10 and the head of the steel pipe pile 1 can be made unnecessary, and the workability can be improved.

  FIG. 4 is a plan sectional view showing a reinforced concrete structure (hereinafter referred to as an RC structure) 100 according to another embodiment. As shown in this figure, in the RC structure 100, the RC beam 101 and the RC beam 102 are orthogonal to each other, and the head portion of the steel pipe pile 1 is embedded at these intersections. The reinforcing bar 14 is divided into left and right in the figure with the steel pipe pile 1 as a boundary, and the main reinforcing bar 14 below the RC beam 102 is divided into the upper and lower parts in the figure with the steel pipe pile 1 as a boundary.

  Here, in the RC structure 100, the fiber reinforced portion 11 is formed so as to surround the steel pipe pile 1, and the end portion of the main reinforcing bar 14 of the RC beam 101 divided in the right and left in the figure and the upper and lower parts in the figure are divided. The end of the main reinforcing bar 14 of the RC beam 102 is fixed to the fiber reinforced portion 11. Therefore, it is possible to transmit the force of the main rebar 14 of the RC beam 101 divided to the left and right in the figure with the steel pipe pile 1 as a boundary, and the main of the RC beam 102 divided to the upper and lower in the figure with the steel pipe pile 1 as a boundary. Transmission of the force of the reinforcing bar 14 becomes possible.

  In addition, the above-mentioned embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof. For example, in the above-described embodiment, the present invention has been described by taking an RC beam or an RC structure in which RC beams intersect in a cross shape as an example, but the present invention is also applied to other concrete structures such as RC slabs. Applicable.

  In the above-described embodiment, the present invention has been described by taking an RC structure embedded with steel pipe piles as inclusions. However, as inclusions, other piles such as cast-in-place piles, columns, walls, Others such as blocks are also included. Moreover, in the above-mentioned embodiment, although this invention was demonstrated taking the case where the steel pipe pile 1 was provided vertically as an example, this invention is applicable even when the steel pipe pile 1 is provided diagonally. In particular, when the steel pipe pile 1 is provided obliquely, a welding operation having a higher degree of difficulty is required as compared with the case where the steel pipe pile 1 is provided vertically, and thus the effect of eliminating the welding operation is great.

  Furthermore, in the above-described embodiment, the end of the main rebar 14 is fixed to the fiber reinforcing portion 11 by providing a mechanical fixing bracket at the end of the main rebar 14. By providing another fixing portion, the end portion of the main reinforcing bar 14 may be fixed to the fiber reinforcing portion 11, and the end portion of the main reinforcing bar 14 may be maintained fixed to the fiber reinforcing portion 11. For example, the straight line may be fixed without providing a hook or the like.

DESCRIPTION OF SYMBOLS 1 Steel pipe pile (inclusion), 10 RC beam (concrete structure), 11 Fiber reinforcement part, 12, 14 Main reinforcement, 15 Shear reinforcement, 16 Mechanical fixing bracket, 100 RC structure (concrete structure), 101 , 102 RC beam (concrete structure)

Claims (2)

A concrete structure in which the main reinforcing bars of the RC structure are divided by inclusions,
The RC structure;
The inclusion;
It is formed of a fiber reinforced cementitious composite material provided so as to continuously surround the inclusion and to be joined to the inclusion, and an annular reinforcing bar or steel material around the inclusion Without being provided, a fiber reinforced portion to which the main reinforcing bar is fixed,
Equipped with a,
The RC structure is joined to the fiber reinforcement;
A concrete structure in which the RC structure does not have a fiber-reinforced portion .   The concrete structure according to claim 1, wherein the inclusion is a pile.

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