JP3020876B2 - Flat deck plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel frame structure, a reinforced concrete structure, a steel reinforced concrete structure, and other steel materials suitable for use as formwork materials and temporary materials for concrete casting such as floors and roof slabs. It relates to a flat deck plate.

[0002]

2. Description of the Related Art A flat deck plate is a reinforcing rib 2 extending continuously over the entire length of a flat portion 1 having a flat upper surface as shown in FIG. Roll-formed from
Most have a length of 1 to 5 m. Here, the reinforcing rib 2
A mating portion 3 of two steel plates, a box-shaped portion 4 located at the lower end thereof, and a box-shaped portion having a triangular cross section as shown in the figure, the bottom surface 4a of the box-shaped portion 4 is It has a drain hole 5 for discharging water seeping from the concrete cast on the flat part 1. The drain hole 5 has a diameter of, for example, 5 mm, and usually has a diameter of 300 to 50 mm.
Plural pieces are formed on the box-shaped portion 4 at a pitch of 0 mm.

[0003] Such a flat deck plate satisfactorily solves human problems in reinforced concrete structures and other floor formwork work, for example, problems with lack of technicians, lack of skill of technicians, and aging. Although it can be obtained, on the other hand, there is a problem that the weight is relatively large among the materials handled by the workers. That is, the materials used for the flat deck plate are SDP1G and SDP2G defined in JIS G 3352. For example, since the yield point of the material is not specified for SDP1G, zinc is generally used for SDP1G. It is plated and has a yield strength of at least 205 N / mm ² and a tensile strength of at least 290 N / mm ² . For such materials, if the sheet thickness is extremely thin, the cross-sectional rigidity is insufficient, and the work load during formwork and the load during concrete placement are concentrated near the center in the length direction. However, since the flat deck plate is likely to buckle in a shape that is inverted from the concentrated part of the load, buckling etc. is likely to occur, so the lower limit of the plate thickness is often set to 0.8 to 1.2 mm. ,
This necessitates an increase in the weight of the flat deck plate.

[0004]

In order to reduce the weight of the flat deck plate, it is most effective to reduce the thickness of the flat deck plate. For example, change the thickness from 1.0mm to 0.75mm
If the weight is reduced to about 25%, the weight can be reduced by about 25%. However, in this case, a reduction in cross-sectional rigidity is unavoidable, and it is effective to use high-strength steel to compensate for this. However, high-strength steels generally have low ductility, and even in experiments conducted by the present inventors, when manufacturing flat deck plates using hot-dip galvanized high-strength steel plates, the first step of forming a drain hole, which is a draining step, is performed. And, in order that the drainage hole in the secondary process is located on the bottom surface of the reinforcing rib, there is no problem in each of the steps of roll forming the reinforcing rib, but in the final step, the reinforcing rib is crushed. During the formation of the obstruction,
It has been clarified that a defect such as cracking or necking is likely to occur in the reinforcing rib starting from the drainage hole near the closed portion. Such defects of the flat deck plate,
In addition, since a local strength-reducing portion is provided, this also tends to cause buckling or the like of the flat deck plate at the time of forming a form, at the time of placing concrete, or otherwise.

Accordingly, an object of the present invention is to solve such a problem and to reduce the weight of a flat deck plate by using a high-strength steel material, and to crack or neck the reinforcing ribs (local elongation). It is an object of the present invention to provide a flat deck plate capable of sufficiently preventing the occurrence of the like. Of course, the present invention is also effective when used for a flat deck plate made of a material specified in JIS or other materials.

[0006]

The flat deck plate of the present invention is made of a plated steel plate, and includes a flat portion, and a reinforcing rib projecting below the flat portion and extending continuously over the entire length of the flat portion. A closure portion formed by crushing and processing the reinforcing rib at both ends of the flat portion, wherein the reinforcing rib comprises a mating portion continuous with the flat portion and a box-shaped portion located at the lower end thereof The drain hole provided in the bottom of the box-shaped part, the inner edge position of the closed part,
More precisely, from the edge position on the side of the reinforcing rib that is not completely crushed, L = 0.7 × YS−140 (mm) YS = distance L expressed by yield strength (N / mm ² ) of plated steel sheet These are separated from each other. In this flat deck plate, by specifying the distance L in particular, it is possible to sufficiently prevent the occurrence of cracks, necking, etc. due to the presence of drain holes in the reinforcing ribs when processing the closed portion of the reinforcing rib. Can be prevented.

[0007] Preferably, the above-mentioned plated steel sheet is made of a high-strength steel having a yield strength (YS) of 335 N / mm ² or more.
It is composed of a high-strength steel such as a steel material solid-solution-strengthened by adding elements such as P and Mn, and a recovery-annealed material obtained by heat-treating an extremely low-carbon steel at a temperature at which recrystallization does not occur. According to such a steel material, the thickness of the plated steel sheet can be reduced, and the flat deck plate can be sufficiently reduced in weight, and the occurrence of cracks in the reinforcing ribs can be prevented.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view in the width direction showing one embodiment of the present invention, and FIG. 2 is a diagram showing a cross-section in the length direction. The illustrated flat deck plate, preferably made of a high-strength steel plated steel plate, is also provided on the lower surface of the flat portion 1 over its entire length, often a plurality of reinforcing ribs 2, as described in the prior art. And closed portions 6 formed by crushing both ends of each reinforcing rib 2. Here, the reinforcing rib 2 has a mating portion 3 of two steel plates and a box-shaped portion 4 having a triangular cross section and located at the lower end of the mating portion 3. Note that the cross-sectional shape of the box-shaped portion 4 can be a polygonal shape other than a triangle. Preferably, the two steel plates of the mating portion 3 are fixed by a spot welding or the like at predetermined intervals in the length direction of the rib 2 except for the closing portion 6.
Reference numeral 7 in the figure indicates the fixing portion.

Here, the position of the drain hole 5 formed in the bottom surface 4a of the box-shaped portion 4 of the reinforcing rib 2 closest to the edge of the flat deck panel is determined by the position of the inner edge of the closing portion 6. In other words, L = 0.7 × YS−140 (mm) YS = Yield point (N / mm ² ) of the plated steel sheet from the boundary position between the closed portion 6 and the reinforcing rib 2 that is not completely crushed. The position is separated by a distance L or more.

The plated steel sheet used in the present invention has a high yield strength (YS) of 335 N / mm ² or more corresponding to SGC 440, preferably high strength of 365 N / mm ² or more equivalent to SGC 490. Use steel.

According to the flat deck plate configured as described above, even if the plated steel plate is formed of a high-strength steel sheet having low ductility in order to reduce the weight of the flat deck plate, water drain holes are formed. Since the reinforcing ribs 2 are located far away from the closing portion 6, when the reinforcing ribs 2 are crushed, there is no possibility that cracks, necking, and the like due to the presence of the drain holes 5 are generated in the reinforcing ribs. Therefore, even when the concrete 8 is cast on the flat deck plate as shown in the drawing, unexpected buckling or the like does not occur on the flat deck plate.

[0012]

EXAMPLES The thickness of the sheet shown in Table 1 as Examples 1 and 2 was
Each of the high-strength steel (SGC490) of 0.75 mm and the recovery annealing material (ultra-low carbon Nb-B steel) and
Flat deck plates were fabricated from 1.0 mm ordinary steel (SGCC) and tested for cracks and necking in the reinforcing ribs due to stress concentration at the drainage holes. Table 2 shows the results.

[0013]

[Table 1]

[0014]

[Table 2]

Meanwhile, each of the flat deck plates is hot-dip galvanized on each steel sheet by controlling the annealing temperature in a continuous hot-dip galvanizing line, and the coating weight is set to Z12 (120 g / m ^{2 on} both sides). In the state, the draining hole 5 is formed in the first step, the reinforcing ribs 2 are formed by a 20-roll roll in the second step, and the shearing processing to a predetermined length is performed in the third step. , Each of which is manufactured by crushing the closed portion 6, and has a length of 2.5 m and two reinforcing ribs. Here, the flat deck plates manufactured as described above, not only those of Comparative Example 1, but also Examples 1 and 2 having a small plate thickness have sufficient strength to pass the certification test of the Ministry of Construction. Has been confirmed to have.

In this test, as is apparent from Table 2, the distance L from the inner edge of the closed portion to the drain edge (diameter 6 mm) of the reinforcing rib 2 (width 40 mm) is used as a parameter. According to Table 2 showing the results of the test, by changing the formation position of the water drainage holes 5 according to the strength of the steel plate, even in the case of a lightweight flat deck plate made of high-strength steel having a small thickness, the reinforcement ribs 2 can be used. It is clear that generation of defects such as cracks can be sufficiently prevented.

[0017]

As is apparent from the above description, according to the present invention, the drainage hole of the reinforcing rib is formed at a position more than a specific distance from the inner edge position of the closing portion. Since the occurrence of defects such as cracks in the reinforcing ribs can be sufficiently prevented, a lightweight flat deck plate using thin high-strength steel can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the width direction showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the flat deck plate shown in FIG. 1;

FIG. 3 is a sectional perspective view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat part 2 Reinforcement rib 3 Interlocking part 4 Box-shaped part 4a Bottom 5 Drainage hole 6 Closed part 7 Fixed part 8 Concrete

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-233253 (JP, A) JP-A-48-40227 (JP, A) JP-A-48-2925 (JP, A) 92913 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) E04B 5/40

Claims (2)

(57) [Claims] 1. A flat portion, a reinforcing rib protruding below the flat portion and extending continuously over the entire length of the flat portion, and a reinforcing rib crushed at both ends of the flat portion. In a flat deck plate having a closed portion formed by processing, a drain hole provided in a bottom surface of the box-shaped portion of the reinforcing rib formed of a mating portion continuous with the flat portion and a box-shaped portion located at the lower end thereof. A flat deck plate which is separated from an inner edge position of the closing portion by a distance L represented by the following formula. L = 0.7 × YS-140 (mm) YS = Yield strength of plated steel sheet (N / mm ² ) 2. The flat deck plate according to claim 1, wherein the plated steel sheet is made of high-strength steel having a yield strength of 335 N / mm ² or more.