JP4541915B2 - Synthetic floor slab - Google Patents

Description

  The present invention relates to a composite floor slab that can be used as a floor slab of a building or a bridge, or a pressure-resistant surface structural member of a structure such as the ocean.

  As a floor slab such as a bridge, a steel-concrete composite slab (hereinafter simply referred to as “synthetic floor slab”) in which concrete is placed on a structural member in which reinforcing bars are arranged on an H-shaped steel or an I-shaped steel is known.

The following Patent Document 1 shows a typical type of such a synthetic floor slab. As shown in FIG. 9, a shape made of I-shaped steel or H-shaped steel on an embedded formwork (bottom plate) 1 made of a steel plate. The steel 2 is arranged at regular intervals, and the concrete 6 is placed on the structural member 5 in which the reinforcing bars 4 are arranged in the holes 3 opened in each shape steel 2.
JP-A-9-221706

  In addition to this, synthetic floor slabs are known that prestress structural steel, reinforcing bars, or cables to prevent the cracking of concrete. In order to reduce weight, expansion with iron powder mixed in The one using concrete is also known.

  In the composite floor slab of Patent Document 1, since the concrete is on the tension side in the negative bending portion or the like, the tensile force is borne only by the reinforcing bars, so the cross section becomes relatively large and the amount of reinforcing bars increases.

  Furthermore, since the penetration amount of deterioration factors increases due to the occurrence of cracks, the problem of corrosion of reinforcing bars and steel plates arises. In addition to the negative bending portion, cracking occurs in the concrete due to drying shrinkage and temperature difference, and water enters from that portion, and the fatigue durability of the floor slab is greatly reduced.

  In addition, since the concrete 6 locks the coarse aggregate in the hole 3 opened in the shape steel 2, there remains a problem in the filling property.

  On the other hand, in order to prevent the occurrence of cracks in the concrete, applying prestress to the structural steel, reinforcing bar, or cable of the structural member is troublesome and uses are limited.

  An object of the present invention is to provide a composite floor slab that eliminates the inconveniences of the conventional example, does not require prestress, prevents cracking of concrete, improves strength, and has good workability. With the goal.

In order to achieve the above object, the present invention according to claim 1 is directed to a steel plate as a mold bottom plate, and ribs provided with a large number of holes distributed in a strip-shaped steel plate with respect to the base plate at appropriate intervals. Arranged in parallel so that these ribs and bottom plate are used as main reinforcing bars, and distribution reinforcing bars are arranged above the ribs in the direction orthogonal to the ribs at appropriate intervals, and the ribs and distribution force are arranged on the bottom plate. to a predetermined thickness of reinforcing bars are embedded, compressive strength 30 N / mm ² or more, a tensile strength of 1.5 N / mm ² or more, cracks dispersion indicated a tensile strain of 1% or more in a tensile test of the cured product of the wood age 28 days A PVA (Polyvinyl Alcohol) short fiber of the following [F1] is added to the formulation matrix of [M1] by 1 to 3 Vol. % High-toughness cement composite material (ECC) that is blended three-dimensionally or two-dimensionally randomly, and ribs are welded to the bottom plate, and high-toughness cement composite material (ECC) The gist is to flow into the plurality of holes of the rib .
[M1]
・ Water binder ratio (W / C) 25% or more
-Sand binding material weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250 kg / m ³ or more and 400 kg / m ³ or less
High-performance AE water reducing agent amount less than 30kg / m ³
[F1]
Fiber diameter 50μm or less
Fiber length: 5-20mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less

  According to the first aspect of the present invention, instead of concrete, by placing a high toughness cement composite material (ECC), this ECC is combined with the rib and the bottom plate and the reinforcing bar to bear the tensile force. The cross section can be reduced even in the negative bending section.

  In addition, the cost can be reduced because the lower structure is smaller. Further, since the crack width is suppressed, the permeation amount of the deterioration factor is reduced, so that the durability is improved. Durability is improved because cracks due to drying shrinkage and temperature difference are also dispersed. Coarse aggregate is not used, and because it exhibits quasi self-filling properties, it is excellent in filling properties.

  In particular, for ribs, high tough cement composite material (ECC) uses coarse aggregates, so that the pores are not blocked and flowability is not hindered.

  Further, by arranging the distribution reinforcing bars at appropriate intervals above the ribs in the direction orthogonal to the ribs, it is possible to distribute the force acting even on the part without the ribs instead of the main reinforcing bars, Cracks due to temperature stress can be suppressed.

  In addition to the above effects, high toughness fiber reinforced cement composite material (high toughness FRC material) has a tensile strain exceeding 1% depending on the matrix and fiber content of the formulation, and is almost perpendicular to the loading direction (stress direction). A crack dispersion type destruction phenomenon occurs in which many cracks (multi cracks) are generated in the direction. Therefore, cracks can be reliably controlled to a minute width.

  Further, the rib can be welded to the bottom plate so as to resist the load at the time of erection and use together with the bottom plate. Further, the high-toughness cement composite material (ECC) is caused to flow into the numerous holes of the ribs, so that the bottom plate is made a composite member with the high-toughness cement composite material (ECC) against a post-dead load and a live load. Can do. In addition, about the rib, when not passing a reinforcing bar through a hole, the fluidity | liquidity of the high toughness cement composite material (ECC) with respect to a hole can be ensured more.

  The gist of the present invention described in claim 2 is that the reinforcing bars are disposed through the holes of the ribs.

  According to this invention of Claim 2, intensity | strength can be ensured more reliably by arrange | positioning such a reinforcing bar.

  The gist of the present invention described in claim 3 is that the reinforcing bar penetrating the hole of the rib is provided with a fixing portion by a hook or a bearing plate at the end.

  According to the third aspect of the present invention, the reinforcing bar penetrating the hole of the rib is provided with a fixing portion by a hook or a bearing plate at the end portion, thereby improving the fixing with the high toughness cement composite material (ECC), and more. Can be effective.

  The gist of the present invention described in claim 4 is that reinforcing reinforcing bars are arranged at appropriate intervals in a direction parallel to the ribs.

  According to the fourth aspect of the present invention, it is possible to further improve the strength by arranging reinforcing reinforcing bars parallel to the ribs as necessary.

  The gist of the present invention described in claim 5 is that a waterproof layer is applied to the surfaces of the steel plate and the rib as the mold bottom plate, and a high toughness cement composite material (ECC) is placed thereon. .

  According to the fifth aspect of the present invention, the durability can be improved by providing the waterproof layer, but the waterproof layer has a higher adhesion to the steel plate than the concrete, so the waterproof layer is applied on the ECC. It is also superior in terms of durability and workability compared to the case of doing.

  As described above, the composite floor slab of the present invention does not need to be prestressed, can prevent cracking of concrete, improve strength, and has good workability.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal front view showing a first embodiment of the composite floor slab of the present invention, FIG. 2 is a longitudinal side view of the same, and 7 is a steel plate forming a bottom plate as a mold.

  On the steel plate 7 forming the bottom plate, ribs 9 provided with a large number of holes 8 distributed in a strip-shaped steel plate were juxtaposed so as to be orthogonal to the bottom plate with appropriate intervals. The rib 9 is welded to the bottom plate 7, and the steel plate 7 and the rib 9 forming the bottom plate are used as a substitute for the main reinforcing bar.

  A waterproof layer 10 is applied to the surfaces of the steel plate 7 and the rib 9 as the mold bottom plate. A commercially available spray-curing waterproof resin coating can be applied to the waterproof layer 10.

  Distributing reinforcing bars 11 are disposed above the ribs 9 at appropriate intervals in a direction orthogonal to the ribs.

Then, a predetermined thickness of the ribs 9 and Hairyoku reinforcing bar 11 on the steel plate 7 and the ribs 9 of the mold bottom plate is embedded, compressive strength 30 N / mm ² or more, a tensile strength of 1.5 N / mm ² or more, the elastic A high toughness cement composite material (ECC) 12 having a coefficient of 15000 N / mm ² or more was cast to form the synthetic floor slab 13 of the present invention. A high toughness cement composite (ECC) 12 flows into the plurality of holes 8 in the rib 9.

This high toughness cement composite material (ECC) 12 is a crack dispersion type in which tensile strain is 1% or more in a tensile test of a cured product on the age of 28 days, and is a PVA (Polyvinyl Alcohol) short fiber of [F1] below 1 to 3 Vol. % Blending amount was three-dimensional random or two-dimensional random.
[M1]
-Water binder ratio (W / C) 25% or more-Sand binder weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250 kg / m ³ or more 400 kg / m ³ or less Air volume when kneaded 20% or more High-performance AE water reducing agent less than 30 kg / m ³ [F1]
Fiber diameter 50 μm or less Fiber length: 5-20 mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less

  In the [M1] preparation matrix, the amount of air when kneaded may be 3.5% or more and 20% or less.

  The tensile strain refers to a strain amount (%) at the maximum tensile stress value in a stress-strain curve obtained by a tensile test of a cured product having a material age of 28 days or more. Actually, it is represented by a tensile strain (%) in a tensile test (for example, a test specimen having a cross section of 30 mm × 13 mm is subjected to a tensile test in an 80 mm test section) on the 28th day of the material age.

  That the tensile strain is 1% or more means that a crack dispersion type fracture phenomenon in which a large number of cracks (multi-cracks) are generated in a direction substantially perpendicular to the loading direction (stress direction).

The vinylon short fiber satisfying the condition of [F1] is preferably a short fiber having a modulus of elasticity equal to or greater than that of concrete manufactured using polyvinyl alcohol resin as a typical material. A high-strength vinylon fiber having a diameter of 0.04 mm and a tensile strength of 1690 N / mm ² is used.

  The materials constituting the high toughness cement composite material (ECC) 12 are cement, admixture, fine aggregate, fiber, and water, and the ratio when the mixing amount is 60 L is as shown in Table 1 below.

  Based on the indoor test results of 18 cases shown in Table 2 below, the cured material properties of the high toughness cement composite material (ECC) 12 will be described below. Case factors were cement type and kneading temperature.

1) Compressive strength and bending strength The compressive strength test was performed using a specimen of φ100 × 200 mm in accordance with JIS A 1108. The bending strength test was performed in accordance with JIS R 5201 using a 40 × 40 × 160 mm specimen. In both tests, three cases are tested in each case, and the lower limit of the confidence interval (m-1.645σ) that allows a 5% defect rate calculated from the average, standard deviation, coefficient of variation, and this data of all data. Asked. In addition, the test material age was 28 days, and curing was performed in a sealed state in an environment at a temperature of 20 ° C. until then.

The test results are shown in Table 3 above. The average value of the compressive strength is at 44.2N / mm ^2. The standard deviation was 5.0 N / mm ² and the coefficient of variation was 11.4%. Average flexural strength was 12.2N / mm ^2, standard deviation 1.5 N / mm ^2, was 11.8% coefficient of variation. 5% the lower limit of the confidence interval which permits defect rate (m-1.645σ) is, 36.0N / mm ² in compression strength, bending strength 9.9N / mm ^2.

2) Tensile strength and tensile strain Fig. 4 shows the tensile test method. Since the test method was not standardized for the direct tensile test, a direct tensile test using a dumbbell specimen (measurement section length 80 mm, width 30 mm, thickness 113 mm) was used. The test material age was 28 days, and curing was performed in a sealed state in an environment at a temperature of 20 ° C. until then.

  The loading speed at the time of the test was 0.5 mm / min, and the tensile strain was evaluated by the average of the two displacement meters 16 attached to both sides of the specimen 15. In the figure, 17 is a displacement meter holder, and 18 is a holder fixing bolt.

  In addition, for the purpose of eliminating the effects of secondary bending, the data for which the displacement of one strain gauge is more than twice that of the other is treated as defective data. Not adopted.

  An example of the stress-strain relationship of the high toughness cement composite material (ECC) 12 is shown in FIG. It can be seen that, unlike ordinary cementitious materials, it exhibits pseudo-strain hardening characteristics in which the stress gradually increases with the increase in tensile strain after the initial cracking. Here, the tensile yield strength and ultimate tensile strain of the high toughness cement composite material (ECC) 12 are defined as shown in FIG. That is, the tensile yield strength was defined as a value corresponding to the lowering yield point of the metal material, and the ultimate tensile strain was established as the maximum strain that could ensure the tensile yield strength. By defining the stress-strain curve on the tensile side of the high toughness cement composite material (ECC) 12 as a complete elastoplastic model, the tensile properties of the high toughness cement composite material (ECC) 12 can be used for the design. become.

  Table 4 below shows the tensile yield strength and ultimate tensile strain calculated from the results of all 84 specimens from which effective test results were obtained.

The average value of the tensile yield strength was 3.8 N / mm ^2, standard deviation 0.4 N / mm ^2, was 10.5% coefficient of variation. The average ultimate tensile strain was 3.0%, with a standard deviation of 1.1% and a coefficient of variation of 37.8%. The lower limit (m−1.645σ) of the confidence interval that allows a 5% defect rate is 3.1 N / mm ^{2 in} tensile yield strength and 1.1% in ultimate tensile strain.

  The ultimate tensile strain of the high toughness cement composite material (ECC) 12 is a value that greatly exceeds the strain (about 0.2%) at the yield level of the steel material.

  As described above, the high toughness cement composite material (ECC) 12 has a high ability to restrain cracks caused by fibers, prevents the expansion of cracks, and generates the next crack. Subsequently, since many new micro cracks are generated one after another, even if an apparently very large tensile strain occurs, it can withstand the load.

  Further, since the crack can be controlled to a minute width (for example, 0.05 mm or less), it is also possible to prevent water penetration from the crack. Even when it is not possible to prevent all penetration from cracks, it is said that the penetration amount is proportional to the cube of the crack width, and the ability to control the crack width can greatly limit the penetration amount.

  And by preventing the penetration of water from cracks, it can be protected from substances such as sulfates and acids that dissolve in water and enter concrete and degrade concrete, which can greatly contribute to the extension of the common life.

  As another embodiment, as shown in FIG. 6, rebars 19 may be disposed by penetrating rebars 19 through a large number of holes 8 of rib 9.

  The reinforcing bar 19 is provided with a fixing part 20 by a hook or a pressure plate at the end. When the fixing part 20 is a hook, it is advanced from the tip of the hook and passed through the hole 8 as shown in FIG. The body portion may be passed through by reversing. In the example of FIG. 7, the hook is U-shaped. Further, the length of the reinforcing bar 19 can be set according to the situation. FIG. 7A shows a long case and FIG. 7B shows a short case. Furthermore, as shown in (C), the direction of the hook may change the phase angle by 90 degrees. (Horizontal, not up / down)

  Further, as shown in FIG. 8, the shape of the hook serving as the fixing unit 20 may be an acute angle hook as shown in (a), a right angle hook as shown in (b), or the like. Further, as shown in FIG. 8 (c), a fixing plate 20 may be used instead of a hook.

  As another embodiment, as shown in FIG. 3, reinforcing reinforcing bars 14 may be arranged at appropriate intervals in a direction parallel to the ribs 9 as necessary.

  Normally, the numerical value in the design can be cleared without arranging the reinforcing bar 14, but the strength can be increased by providing the reinforcing bar 14.

1 is a longitudinal front view showing a first embodiment of a composite floor slab of the present invention. 1 is a longitudinal sectional side view showing a first embodiment of a composite floor slab of the present invention. It is a vertical side view which shows 2nd Embodiment of the synthetic floor slab of this invention. It is explanatory drawing which shows a direct tensile test method. It is a graph which shows tensile performance. It is a vertical front view which shows 2nd Embodiment of the synthetic floor slab of this invention. It is explanatory drawing which shows the arrangement | positioning method of the reinforcing bar in 2nd Embodiment of the synthetic floor slab of this invention. It is explanatory drawing which shows the modification of the reinforcing bar in 2nd Embodiment of the synthetic floor slab of this invention. It is a perspective view which shows a prior art example.

DESCRIPTION OF SYMBOLS 1 ... Burial formwork (bottom plate) 2 ... Shape steel 3 ... Hole 4 ... Reinforcement 5 ... Structural member 6 ... Concrete 7 ... Steel plate 8 ... Hole 9 ... Rib 10 ... Waterproof layer 11 ... Power distribution reinforcement 12 ... High toughness cement composite Material (ECC)
DESCRIPTION OF SYMBOLS 13 ... Composite floor slab 14 ... Reinforcing bar 15 ... Specimen 16 ... Displacement meter 17 ... Displacement meter holder 18 ... Holder fixing bolt 19 ... Reinforcing bar 20 ... Fixing part

Claims (5)

On the steel plate as the formwork bottom plate, ribs with a large number of holes distributed in the strip-shaped steel plate are arranged side by side so as to be orthogonal to the bottom plate at appropriate intervals. Further, the reinforcing bars are arranged at appropriate intervals above the ribs in a direction orthogonal to the ribs, and the compression strength is 30 N / mm ² to a predetermined thickness where the ribs and the reinforcing bars are embedded on the bottom plate. As described above, it is a crack dispersion type having a tensile strength of 1.5 N / mm ² or more and a tensile strain of 1% or more in a tensile test of a cured product on the 28th day of the material age, and has the following [F1] PVA (Polyvinyl Alcohol) short. The fiber is added to the formulation matrix of [M1], exceeding 1 and 3 Vol. % High-toughness cement composite material (ECC) that is blended three-dimensionally or two-dimensionally randomly, and ribs are welded to the bottom plate, and high-toughness cement composite material (ECC) Is a synthetic floor slab characterized by flowing into the plurality of holes of the rib .
[M1]
・ Water binder ratio (W / C) 25% or more
-Sand binding material weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250 kg / m ³ or more and 400 kg / m ³ or less
High-performance AE water reducing agent amount less than 30kg / m ³
[F1]
Fiber diameter 50μm or less
Fiber length: 5-20mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less   The composite floor slab according to claim 1, wherein reinforcing bars are disposed through the holes of the ribs.   The composite floor slab according to claim 2, wherein the reinforcing bar penetrating the hole of the rib is provided with a fixing portion by a hook or a pressure plate at the end.   The composite floor slab according to any one of claims 1 to 3, wherein reinforcing reinforcing bars are disposed at appropriate intervals in a direction parallel to the ribs.   The synthetic floor slab according to any one of claims 1 to 4, wherein a waterproof layer is applied to the surfaces of the steel plate and ribs as the mold bottom plate, and a high toughness cement composite material (ECC) is placed thereon.

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