Deck synthetic slab

Abstract

To reduce the weight of a deck composite slab and the construction cost of a floor slab without lowering the crack spread preventing performance and strength of the deck composite slab.SOLUTION: In the deck composite slab (1) including a deck plate (10) in which a crest portion (11) and a trough portion (13) are alternately continued, concrete (60) placed on one surface of the deck plate (10), and a crack prevention member (63) embedded in the concrete (60), the crack prevention member (63) is a welded metal mesh in which a plurality of iron wires (64) having nodes are intersected and joined at the intersection portions. The ratio of the cross-sectional area of the welded wire mesh to the concrete cross-sectional area above the crest part (11) of the deck plate (10) in one axial direction is 0.18% or more and less than 0.2%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite deck slab. [Background technology]

[0002] Composite deck slabs, which are made by integrating a deck plate and concrete, are known. Composite deck slabs support the load acting on the floor as a composite structure in which the deck plate bears tensile forces and the concrete bears compressive forces (see, for example, Patent Document 1). The drying speed and deformation performance of composite deck slabs differ between the weak and strong axis directions of the deck plate. Therefore, welded wire mesh and rebar are embedded in the concrete to prevent cracks in the composite deck slab from expanding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-41348 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the minimum cross-sectional area of ​​the welded wire mesh or reinforcing bars installed to prevent the expansion of cracks in the deck composite slab is set as the standard, at 0.2% or more of the cross-sectional area of ​​the concrete above the peak of the deck plate (peak concrete cross-sectional area). However, increasing the proportion of welded wire mesh and rebar increases the weight of the deck composite slab and leads to a rise in the cost of constructing the floor slab, so there is a need to reduce the weight of the deck composite slab and the cost of constructing the floor slab without compromising its crack prevention performance or strength.

[0005] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a technology that can reduce the weight of deck composite slabs and reduce the cost of building floor slabs without reducing the crack expansion prevention performance or strength of the deck composite slab. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention is a deck composite slab comprising a deck plate with alternating peaks and valleys, concrete poured on one side of the deck plate, and a crack prevention member embedded in the concrete, wherein the crack prevention member is a welded wire mesh formed by crossing a plurality of iron wires having nodes on their surface and joining them at the intersections, and the ratio of the cross-sectional area of ​​the welded wire mesh to the cross-sectional area of ​​the concrete above the peaks of the deck plate in one axial direction is 0.18% or more and less than 0.2%.

[0007] The iron wire constituting the welded wire mesh is preferably a deformed iron wire.

[0008] The wire diameter of the deformed iron wire is preferably 3 to 9 mm.

[0009] In addition, it is preferable that the interval between adjacent deformed iron wires in the welded wire mesh is 50 to 300 mm.

[0010] The area per unit length of the cross section intersecting the axial direction of the deformed iron wire is 1.8 cm 2 / m is preferred.

[0011] Furthermore, it is preferable that the thickness of the concrete above the crest of the deck plate in one axial direction is 50 to 200 mm.

[0012] Preferably, the deck plate has a height of the peaks of 50 to 150 mm, a width of the peaks and valleys of 30 to 210 mm, and a plate thickness of 0.5 to 3.2 mm. [Effects of the Invention]

[0013] According to one aspect of the present invention, it is possible to reduce the weight of a deck composite slab and reduce the cost of building a floor slab without reducing the crack propagation prevention performance or strength of the deck composite slab. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing a portion of a deck composite slab. [Figure 2] FIG. [Figure 3] This is a view of the deck composite slab from the short side (minor axis direction). [Figure 4] This is a view of the deck composite slab from the longitudinal direction (strong axis direction). [Figure 5] 1 is a table showing details of each part of the test specimen. [Figure 6] 1 is a table showing the concrete mix of the test specimen. [Figure 7] 1 is a table showing the results of a fresh test on the concrete of the test specimens. [Figure 8] FIG. 1 is a diagram showing the installation positions of strain gauges on a test specimen. [Figure 9] FIG. 1 is a diagram showing the installation positions of strain gauges on a test specimen. [Figure 10] FIG. 1 is a diagram showing the installation positions of strain gauges on a test specimen. [Figure 11] 1 is a graph showing measurement results of shrinkage strain of concrete of test specimens. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the following description, the drawings are schematic, and the dimensional relationships and ratios of elements may differ from the actual ones. The dimensional relationships and ratios may differ between the drawings.

[0016] <Deck composite slab> Figure 1 is a perspective view showing a portion of a deck composite slab. Figure 3 is a view of the deck composite slab as seen from the short side (minor axis direction). Figure 4 is a view of the deck composite slab as seen from the long side (strong axis direction). As shown in Figures 1, 3, and 4, the composite deck slab 1 is a composite structure including, for example, a steel deck plate 10 and concrete 60. It is used for the roof, rooftop, or floor of a building constructed of steel, reinforced concrete, or wood. In the composite deck slab 1, the deck plate 10 resists tensile force, and the concrete 60 resists compressive force. This allows the composite deck slab 1 to withstand large loads and span a long distance between support beams B made of steel, such as H-shaped steel. The composite deck slab 1 has a deck plate 10 attached to its underside, and concrete 60 poured and solidified on top of the deck plate 10 to form a concrete slab. Therefore, when the composite deck slab 1 is installed between support beams B, the underside of the deck plate 10 is exposed to the floor directly below. Note that the support beams B are not limited to steel; they may be reinforced concrete, lumber, or wood.

[0017] In the following description, the direction in which the deck plate 10 is spanned between the support beams B of the building is referred to as the longitudinal direction (length direction, strong axis direction) L of the deck plate 10, the direction in which the deck plate 10 extends intersecting the longitudinal direction L is referred to as the short direction (width direction, weak axis direction) W, and the direction in which the deck plate 10 is placed on the support beams B is referred to as the height direction H of the deck plate 10.

[0018] FIG. 2 is a perspective view of the deck plate. As shown in FIG. 2, the deck plate 10 is a corrugated steel plate formed by, for example, roll-forming a thin steel plate that has been subjected to a surface treatment such as galvanization. The deck plate 10 does not necessarily have to be subjected to a surface treatment such as plating. The deck plate 10 has peaks 11, valleys 13, and inclined portions 15. The deck plate 10 has a plurality of peaks 11 and valleys 13 formed alternately, with adjacent peaks 11 and valleys 13 connected by inclined portions 15. The deck plate 10 has a corrugated shape in which the peaks 11 and valleys 13, each extending in the longitudinal direction L, are connected to each other in the lateral direction W via the inclined portions 15.

[0019] The deck plate 10 has, for example, two peaks 11, one valley 13, and two pairs of inclined portions 15, and is formed in a corrugated shape in a cross section along the short side direction W. Note that, depending on the dimension of the deck plate 10 in the short side direction W, only one peak 11 may be provided on one deck plate 10. Furthermore, when one deck plate 10 is connected to another deck plate 10 in the short side direction W, the connection portion between the deck plates 10 functions as a valley 13. Furthermore, the deck plate 10 may be end-closed at both ends in the longitudinal direction L. Specifically, the deck plate 10 preferably has, for example, peaks 11 with a height of 50 to 150 mm, peaks 11 and valleys 13 with a width of 30 to 210 mm, and a plate thickness of 0.5 to 3.2 mm.

[0020] The peak portion 11 is a flat portion located above the support beam B when the deck plate 10 is spanned between the support beams B (hereinafter also referred to as the "spanning state"), and is a plate-shaped portion extending in the longitudinal direction L. The peak portion 11 has a groove 12. The groove 12 is formed so as to be recessed toward the underside of the deck plate 10. The groove 12 extends in the longitudinal direction L, and when there is only one groove 12, it is provided near the center in the lateral direction W. The grooves 12 in the ridge portions 11 improve the strength of the ridge portions 11. The number of grooves 12 formed in the ridge portions 11 is not limited to one, and multiple grooves 12 may be formed. The grooves 12 may be formed discontinuously along the longitudinal direction L. Note that the grooves 12 may not be formed.

[0021] The valley portions 13 are parallel or approximately parallel to the peak portions 11 and are flat portions that are placed on the support beam B in a bridging state. The valley portions 13 are plate-shaped portions that extend in the longitudinal direction L. The valley portions 13 do not overlap with the peak portions 11 in the lateral direction W. Note that the grooves 12 formed in the peak portions 11 may also be formed in the valley portions 13. The valley portion 13 has a protrusion 14. The protrusion 14 is formed so as to protrude toward the upper surface side of the deck plate 10. The protrusion 14 extends in the longitudinal direction L, and when there is only one protrusion 14, it is provided near the center in the lateral direction W. The protrusions 14 in the valleys 13 improve the strength of the valleys 13. The number of protrusions 14 formed in the valleys 13 is not limited to one, and a plurality of protrusions 14 may be formed. The protrusions 14 may be formed discontinuously along the longitudinal direction L. Note that the protrusions 14 may not be formed.

[0022] The inclined portions 15 are portions that connect the peaks 11 and the valleys 13, and are plate-shaped portions that extend in the longitudinal direction L. The inclined portions 15 extend obliquely from the side edges of the peaks 11 toward the side edges of the valleys 13 in the short direction W. The inclined portions 15 are inclined to form a predetermined angle, for example, an obtuse angle, with the peaks 11 and the valleys 13. Note that the grooves 12 formed in the peaks 11 may be formed in the inclined portions 15.

[0023] The inclined portion 15 has an engagement portion 16. The engagement portion 16 is a convex portion formed so as to protrude from the surface of the inclined portion 15 toward the upper surface of the deck plate 10. The engagement portions 16 are formed, for example, by embossing, and a plurality of engagement portions 16 are provided at predetermined intervals along the extension direction (longitudinal direction L) of the inclined portion 15. The engagement portions 16 increase the strength of the inclined portion 15 and promote engagement between the concrete 60 and the deck plate 10, thereby enhancing the composite effect of the deck composite slab 1. The engagement portions 16 may extend in the longitudinal direction L.

[0024] A bulge 17 is formed at the transition between the valley 13 and the inclined portion 15. The bulge 17 is a portion that protrudes in opposite directions from a pair of inclined portions 15 in one peak 11. That is, the bulge 17 in a pair of inclined portions 15 that face each other across the valley 13 are formed to face each other and bulge in directions that bring them closer to each other. The bulge 17 is located on the valley 13 side of the engagement portion 16. The bulge 17 may be formed discontinuously along the longitudinal direction L.

[0025] A groove 18 is formed in the transition between the bulge portion 17 and the valley portion 13. The groove 18 is formed as an engagement groove (dovetail groove) extending along the longitudinal direction L. The cross section of the groove 18 along the short direction W is formed to be curved. The groove 18 is formed in a pair of inclined portions 15 of one peak portion 11 in a direction approaching each other. That is, in a pair of inclined portions 15 continuing to the valley portion 13 of the deck plate 10, the grooves 18 are formed to face each other and curve in a direction away from each other. The grooves 18 may be formed intermittently along the longitudinal direction L. The grooves 18 promote engagement between the concrete 60 and the deck plate 10, enhancing the composite effect of the deck composite slab 1.

[0026] The concrete 60 is formed by solidifying concrete poured on the deck plate 10. Reinforcing members 61 for reinforcing the deck composite slab 1 may be provided inside the concrete 60. The concrete 60 is provided on the deck plate 10 so that the thickness above the crests 11 of the deck plate 10 in one axial direction is, for example, 50 to 200 mm. Examples of the reinforcing member 61 include a stud 62 joined to the flange of the support beam B so as to stand along the height direction H, as shown in Figures 1, 3, and 4, and a crack prevention member 63 that prevents cracks in the concrete 60. The studs 62 are arranged in the short direction W on the flange of the support beam B. The crack prevention members 63 are provided along the surface direction of the peak portion 11 at intervals in the height direction (vertical direction) from the upper surface of the deck plate 10 (deck plate 10). By providing the studs 62 on the support beams B, in addition to the deck plate 10, the integration of the studs 62 with the concrete 60 can be increased, and the deck composite slab 1 can be reinforced. A plurality of studs 62 are provided on the flange of the support beam B along the extending direction of the flange, but they are not limited to the studs 62 and may be welded by burn-out plug welding or the like.

[0027] The crack prevention member 63 is a welded wire mesh made by crossing a plurality of deformed iron wires 64 having a plurality of nodes on the surface and joining them at the intersections. The crack prevention member 63 has, for example, a wire diameter of 3 to 9 mm and an area per unit length of a cross section intersecting the axial direction of 1.8 cm 2 The deformed iron wires 64 are crossed with each other so that the interval (pitch) between adjacent deformed iron wires 64 is 50 to 300 mm. For example, a deformed iron wire welded wire mesh conforming to the CD6 standard is used. In other words, the thickness of the convex concrete, the diameter of the deformed iron wires 64, and the spacing (pitch) of the deformed iron wires 64 are set so that the ratio of the cross-sectional area of ​​the crack prevention member (deformed iron wire welded wire mesh) 63 to the cross-sectional area of ​​the concrete (convex concrete) above the convex portions 11 of the deck plate 10 in the strong axis direction is 0.18% or more and less than 0.2%. Therefore, as long as the ratio of the cross-sectional area of ​​the deformed iron wire welded wire mesh to the cross-sectional area of ​​the convex concrete is 0.18% or more and less than 0.2%, the deck composite slab 1 can be formed by freely combining the thickness of the convex concrete, the diameter of the deformed iron wires 64 in the deformed iron wire welded wire mesh, and the spacing (pitch) of the deformed iron wires 64.

[0028] Such reinforcing members 61 improve the bearing capacity of the ends of the composite deck slab 1, improve the degree of fixation to the support beams B, and suppress the occurrence and expansion of cracks in the composite deck slab 1, thereby increasing the allowable performance of the live load and span. In other words, stress generated around the studs 62 can be dispersed to reinforce the ends of the composite deck slab 1, thereby improving structural performance and fire resistance. In addition, in the above-mentioned reinforcing member 61, the reinforcing bars and reinforcing steel plates, etc. arranged around the studs 62 and support beams B can reinforce the ends of the deck composite slab 1 (near the support beams B), and the crack prevention members 63 arranged throughout the concrete 60 and the reinforcing bars and reinforcing steel plates, etc. installed at any location can also reinforce areas other than the ends of the deck composite slab 1 (such as the center of the deck composite slab 1).

[0029] Furthermore, the crack prevention member 63 embedded in the concrete 60 is a welded wire mesh made of deformed iron wires 64 with nodes on their surface formed into a net shape, so the intersections of the deformed iron wires 64 restrain the concrete 60 that they come into contact with, preventing it from moving. The nodes in the deformed iron wires 64 also restrain the concrete that they come into contact with, preventing it from moving. As a result, the crack prevention member 63 combines the advantages of both conventional welded wire mesh and deformed steel bars, making it possible to more effectively prevent cracks and crack expansion in the deck composite slab 1. Here, the minimum cross-sectional area of ​​the welded wire mesh or reinforcing bars installed to prevent the expansion of cracks in the deck composite slab 1 is standard to be 0.2% or more of the cross-sectional area of ​​the concrete 60 above the peak 11 of the deck plate 10 (peak concrete cross-sectional area), but by using a deformed iron wire welded wire mesh as the crack prevention member 63, it is possible to make the cross-sectional area ratio 0.18% or more and less than 0.2%. Therefore, the weight of the deck composite slab 1 can be reduced and the cost of constructing the floor slab can be reduced without reducing the crack expansion prevention performance and strength of the deck composite slab 1.

[0030] <Evaluation of crack prevention materials> In order to confirm the effectiveness of crack prevention materials embedded in the concrete of deck composite slabs in preventing cracks and preventing crack expansion, three types of deck composite slab test specimens were prepared, and tests were conducted to measure and compare the shrinkage strain of each concrete. As shown in Figures 5 to 10, the composite deck slab specimens all had a width (length along the weak axis) of 600 mm, a height of 175 mm, and a depth (length along the strong axis) of 250 mm. The deck plates used for the specimens were steel plates with a hot-dip galvanized Z12 coating on the surface, with a peak height of 75 mm, a peak and valley width of 120 mm, and a plate thickness of 1.0 mm. The concrete poured into the deck plates was ordinary concrete with the mix shown in Figures 6 and 7, and the concrete peak slab thickness (the distance from the peak to the top surface of the concrete) was 100 mm.

[0031] Specimen A used a welded wire mesh as a crack prevention member, in which round steel wires were arranged in a grid pattern and the intersections of the round steel wires were welded together. The welded wire mesh had a wire diameter of 6 mm and the spacing between adjacent round steel wires (mesh spacing) was 100 mm. The cross-sectional area of ​​the welded wire mesh is 0.28 cm 2 , the cross-sectional area per 1 m in the weak axis direction is 2.8 cm 2 / m, and the ratio of the cross-sectional area of ​​the welded wire mesh to the cross-sectional area of ​​the concrete on the top of the crest above the crest of the deck plate along the weak axis is 0.28%.

[0032] Specimen B used deformed reinforcing bars as crack prevention members. The deformed reinforcing bars were D10 standard and were placed at intervals of 200 mm in the strong axis direction. The cross-sectional area of ​​the deformed steel bar is 0.71 cm 2 , the cross-sectional area per 1m in the weak axis direction is 3.5cm 2 / m, and the ratio of the cross-sectional area of ​​the deformed steel bars to the cross-sectional area of ​​the concrete on the convex part above the convex part of the deck plate along the weak axis is 0.35%.

[0033] Specimen C used a welded wire mesh made of deformed iron wires arranged in a grid pattern and welded together at their intersections as a crack prevention material. The welded wire mesh conforms to the CD6 standard (pitch width 150 mm). The cross-sectional area of ​​the deformed welded wire mesh is 0.28 cm 2 , the cross-sectional area per meter in the weak axis direction is 1.8 cm 2 / m, and the ratio of the cross-sectional area of ​​the deformed wire welded wire mesh to the cross-sectional area of ​​the concrete on the top of the crest above the crest of the deck plate along the weak axis is 0.18%.

[0034] In each specimen, a strain gauge was embedded in the concrete to measure shrinkage strain at each age of the concrete. 8 to 10, each test specimen was provided with three strain gauges 71 to 73. The strain gauges 71 to 73 were supported by supporting members such as piano wires that had a strength that did not contribute to preventing cracks. The strain gauge 71 was installed above the inclined portion 15 between the peak portion 11 and the valley portion 13, 30 mm from the top surface of the concrete 60 and 150 mm along the strong axis direction from the front to the back of the test specimen. The strain gauge 72 was installed above the valley portion 13, at a position 30 mm from the top surface of the concrete 60 and 100 mm along the strong axis from the front to the back of the test specimen. The strain gauge 73 was installed above the ridge 11, 30 mm from the top surface of the concrete 60 and 100 mm along the strong axis from the front to the back of the test specimen. The strain measurements by the three strain gauges 71 to 73 were averaged to measure the strain for each material age.

[0035] Figure 11 is a graph showing the measurement results of shrinkage strain of concrete up to the age of 180 days. As shown in Figure 11, the deck composite slab 1 in which the deformed iron wire welded wire mesh 63 is embedded in the concrete 60 has the smallest ratio of the cross-sectional area of ​​the deformed iron wire welded wire mesh 63 to the cross-sectional area of ​​the concrete on top, yet it has the smallest shrinkage strain. This shows that by using a deformed iron wire welded wire mesh as a crack prevention member 63, the design standards for the deck composite slab 1 can be met even if the ratio of the cross-sectional area of ​​the deformed iron wire welded wire mesh 63 to the cross-sectional area of ​​the hill-top concrete is less than the conventional standard of 0.2%.

[0036] <Other> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and includes all aspects encompassed by the concept of the present invention and the scope of the claims. Furthermore, each configuration may be appropriately and selectively combined to achieve at least some of the above-described problems and effects. Furthermore, for example, the shape, material, arrangement, size, etc. of each component in the above embodiments may be appropriately modified depending on the specific use of the present invention. For example, the ratio of the cross-sectional area of ​​the deformed wire welded wire mesh 63 to the cross-sectional area of ​​the hill-top concrete can be made less than the conventional standard of 0.2% by using deformed wire welded wire mesh 63 of CD4, CD5, or CD5.5, rather than being limited to CD6 standard. Furthermore, the shape of the deck plate 10 is not limited to the shape in the above embodiment, but can be changed. [Explanation of symbols]

[0037] 1 Deck composite slab 10 Deck Plate 11 Yamabe 12 grooves 13 Valley 14 Convex part 15 Slope 16 Engagement part 17 Bulge 18 groove 60 Concrete 61 Reinforcement member 62 studs 63 Deformed steel wire welded mesh (crack prevention material) 64 Deformed Iron Wire 71 Strain gauge 72 Strain gauge 73 Strain Gauge

Claims

1. A composite deck slab comprising a deck plate having alternating peaks and valleys, concrete poured on one surface of the deck plate, and a crack prevention member embedded in the concrete, The crack prevention member is a welded wire mesh formed by crossing a plurality of iron wires having nodes on their surfaces and joining them at the crossings, A composite deck slab characterized in that the ratio of the cross-sectional area of ​​the welded wire mesh to the cross-sectional area of ​​the concrete above the crest of the deck plate in one axial direction is 0.18% or more and less than 0.2%.

2. 2. The composite deck slab according to claim 1, wherein the iron wire constituting the welded wire mesh is a deformed iron wire.

3. 3. The composite deck slab according to claim 2, wherein the wire diameter of the deformed iron wire is 3 to 9 mm.

4. The composite deck slab according to claim 2 or 3, characterized in that the spacing between adjacent deformed iron wires in the welded wire mesh is 50 to 300 mm.

5. The area per unit length of the cross section intersecting the axial direction of the deformed iron wire is 1.8 cm ２ 4. The composite deck slab according to claim 2 or 3, characterized in that:

6. 3. The composite deck slab according to claim 1, wherein the thickness of the concrete above the crest of the deck plate in one axial direction is 50 to 200 mm.

7. The deck plate has a height of the peaks of 50 to 150 mm, a width of the peaks and valleys of 30 to 210 mm, and a plate thickness of 0.5 to 3.2 mm.

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