JP7763809B2 - Deck plate and deck composite slab - Google Patents

Description

The present invention relates to deck plates and composite deck slabs.

The floors of mid- to high-rise buildings are often constructed with composite deck slabs, which are formed by integrating deck plates and concrete. Composite deck slabs support the load acting on the floor as a composite structure in which the deck plates bear tensile forces and the concrete bears compressive forces.
Because the deck plate is located on the floor directly below, if the heat of a fire causes it to lose its strength, it will lose its function as a material that constitutes the composite deck slab structure. Therefore, composite deck slabs are known that reinforce the support points, which are the joints between the beams and the composite deck slab, to improve the allowable performance of loads, spans, etc., and fire resistance (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-41348

In a composite deck slab like the one above, if areas prone to collapse in the event of a fire are reinforced, areas other than the reinforced areas may become new weak points, which could lead to collapse from these new weak points.

The present invention was developed in consideration of the above-mentioned issues, and aims to provide technology that can eliminate the weaknesses of deck composite slabs and prevent collapse.

To solve the above problem, one aspect of the present invention is a composite deck slab comprising a deck plate placed on a support beam and a concrete portion poured on the upper surface of the deck plate, characterized in that it includes a wooden portion provided on the underside of the deck plate main body so as to expose the deck plate main body in the reinforced area of the composite deck slab.

Furthermore, it is preferable that the reinforced area be near the support beam on which the deck plate is placed.

Furthermore, it is preferable that the longitudinal ends of the deck plate main body in the area not placed on the support beam are exposed by a predetermined distance.

It is also preferable that the wooden portion be located on the underside of the deck plate main body, excluding mounting positions for wall materials, etc.

It is also preferable to provide a reinforcing member to reinforce the concrete portion.

In order to solve the above problems, one aspect of the present invention is a deck plate used in a composite deck slab, which has a wooden portion provided on the underside of the deck plate, and is characterized in that the wooden portion is provided so as to expose the deck plate main body portion in the reinforced area of the composite deck slab that is reinforced when concrete is poured on the upper surface of the deck plate to construct the composite deck slab.

Furthermore, it is preferable that the reinforced area be near the support beam on which the deck plate is placed.

It is also preferable that the wooden portion is formed from decorative finishing materials.

One aspect of the present invention makes it possible to eliminate weaknesses in deck composite slabs and prevent collapse.

FIG. 1 is a perspective view showing a portion of a deck composite slab. FIG. This is a view of the deck composite slab from the short side. This is a view of the deck composite slab viewed from the longitudinal direction. 1 is a table illustrating the relationship between wood thickness and fire resistance time. 1 is a table illustrating the relationship between the reinforcement area of a deck composite slab and the area that is not covered with wood. 10 is a table illustrating an example of the relationship between the reinforcement area of a deck composite slab and the area that is not covered with wood. 10 is a graph comparing the amount of deflection of a deck composite slab without wood and a deck composite slab with wood when heated. 10 is a graph comparing the maximum temperatures of the top surface of a composite deck slab without wood and a composite deck slab with wood when heated.

Embodiments of the present invention will be described below with reference to the drawings. Please note that the drawings are schematic and the dimensional relationships and ratios of elements may differ from reality. Dimensional relationships and ratios may differ between the drawings.

<Deck composite slab>
Fig. 1 is a perspective view showing a part of a deck composite slab. Fig. 3 is a view of the deck composite slab as seen from the short side direction. Fig. 4 is a view of the deck composite slab as seen from the long side 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 a concrete section 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 section 60 resists compressive force. This allows the composite deck slab 1 to withstand large loads and span a long span between support beams B made of steel, such as H-shaped steel. The composite deck slab 1 has the deck plate 10 attached to its underside, and concrete is poured onto the upper surface of the deck plate 10 and solidifies integrally to form the concrete section 60. Therefore, when the composite deck slab 1 is spanned 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, and may be made of reinforced concrete, lumber, or wood.

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) 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 transverse direction (width 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.

(Deck plate)
FIG. 2 is a perspective view of the deck plate.
As shown in FIG. 2 , the deck plate 10 includes a deck plate main body 10 a and a wooden portion 20 .
The deck plate main body 10a is a corrugated steel plate formed by roll-forming or the like from a thin steel plate that has been subjected to a surface treatment such as zinc plating. The deck plate main body 10a does not necessarily have to be subjected to a surface treatment such as plating. The deck plate main body 10a has peaks 11, valleys 13, and inclined portions 15. The deck plate main body 10a 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 main body 10a has a wave-like 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.

The deck plate main body 10a has, for example, two peaks 11, one valley 13, and two pairs of inclined portions 15, and is formed in a wave-like shape in cross section along the short side direction W. Depending on the dimensions of the deck plate 10 in the short side direction W, only one peak 11 may be provided on one deck plate main body 10a. Furthermore, when one deck plate 10 is connected to another deck plate 10 in the short side direction W, the connection between the deck plates 10 functions as a valley 13. The deck plate 10 may also be end-closed at both ends in the longitudinal direction L.

The ridge 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 at all.

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 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 multiple 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.

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 respect to 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.

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 multiple 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 portion 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.

Bulges 17 are formed at the transition between the valleys 13 and the inclined portions 15. The bulges 17 are portions that protrude in opposite directions on a pair of inclined portions 15 of one peak 11. That is, the bulges 17 on a pair of inclined portions 15 that face each other across the valley 13 are formed to face each other and bulge toward each other. The bulges 17 are located on the valley 13 side of the engagement portion 16. The bulges 17 may be formed intermittently along the longitudinal direction L.

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

A wooden portion 20 is provided on the underside of the deck plate 10 (the underside of the deck plate main body 10a). The wooden portion 20 is, for example, a wooden board formed into a plank shape and fixed to the underside of the valley portions 13 using screws or the like. The wooden portion 20 may be not only sawn lumber, but also so-called engineered wood such as laminated lumber or LVL, which has been treated with chemicals or added with resin to improve its strength, fire resistance, flame retardancy, or both. It may also be wood that has improved resistance to mold and decay fungi. The wooden portion 20 may be attached to the deck plate main body 10a using any method other than screws, as long as it is attached using adhesive or other means. The wooden portion 20 is not limited to being attached so as to be in direct contact with the underside of the valley portions 13 of the deck plate main body 10a. The wooden portion 20 may also be attached at a distance from the underside of the valley portions 13 of the deck plate main body 10a via a member such as a pipe or steel material. In other words, the deck plate 10 only needs to have the wooden portion 20 attached directly or indirectly by some means to the underside of the deck plate main body 10a.
The wooden portion 20 is a decorative finishing material that covers the underside of the deck plate 10 that is exposed to the floor directly below between the support beams B when the deck plate 10 is placed on the support beams B, thereby improving the appearance.
The wooden portion 20 is formed to have a thickness calculated by multiplying the fire resistance time (fire resistance performance) to be added to the deck composite slab 1 by the carbonization rate of the wooden portion 20.

FIG. 5 is a table illustrating the relationship between the thickness of the wood portion 20 and the fire resistance time.
Specifically, as shown in Figure 5, if the carbonization rate of the wood that makes up the wooden part 20 is 0.65 mm/min and you want to add 30 minutes of fire resistance to the deck composite slab 1, the thickness of the wooden part 20 should be 0.65 mm/min x 30 min = 19.5 mm.
Similarly, as shown in FIG. 5, if it is desired to add 30 to 60 minutes of fire resistance to the deck composite slab 1, the thickness of the wooden part 20 should be 19.5 to 39.0 mm, and if it is desired to add 60 to 120 minutes of fire resistance to the deck composite slab 1, the thickness of the wooden part 20 should be 39.0 to 78.0 mm.
If it is desired to add 120 to 180 minutes of fire resistance to the composite deck slab 1, the thickness of the wooden part 20 should be 78.0 to 117.0 mm. The carbonization rate of the wood does not have to be 0.65 mm, and the thickness of the wooden part 20 will vary depending on the carbonization rate.

Furthermore, the composite deck slab 1 may have a predetermined fire resistance even in an uncoated state, i.e., when the deck plate 10 is not coated and no wooden members 20 are provided. For example, if the composite deck slab 1 has a fire resistance time (fire resistance performance) of 120 minutes in an uncoated state, providing a 39 mm thick wooden member 20 on the underside of the deck plate 10 can ensure that the composite deck slab 1 has a fire resistance time of 180 minutes, which is the sum of the 120 minute fire resistance time of the composite deck slab 1 itself and the 60 minute fire resistance time of the wooden member 20. On the other hand, if a 180 minute fire resistance time of the composite deck slab 1 with this deck plate 10 is desired, the wooden member 20 can be formed to a thickness of 39 mm, which is the thickness required for the remaining 60 minutes of fire resistance, by subtracting the 120 minute fire resistance time of the composite deck slab 1 itself.

The wooden part 20 may also be subjected to a fireproofing treatment that provides fire resistance for a predetermined period of time. For example, if the wooden boards that make up the wooden part 20 are treated (e.g., with a chemical solution) to provide fireproofing (ensuring a fireproof time of 20 minutes), semi-fireproofing (ensuring a fireproof time of 10 minutes), or fire-retardanting (ensuring a fireproof time of 5 minutes), the wooden part 20 can be thinned by a thickness equal to the product of the fireproof time and the carbonization rate.
Specifically, if it is desired to add fire resistance performance of 120 minutes to the deck composite slab 1, and the wooden part 20 has been treated to have non-combustibility (ensuring a non-combustibility time of 20 minutes), the thickness of the wooden part 20 should be such that it has a fire resistance time of 100 minutes, which is the fire resistance time of 120 minutes minus the non-combustibility time of 20 minutes due to the non-combustibility treatment, i.e., 0.65 mm/min x 100 min = 65.0 mm.

In this way, since the wooden portion 20 is provided on the underside of the deck plate 10, the wooden portion 20 will be the first to heat up in the event of a fire. Therefore, by forming the deck composite slab 1 to a thickness that provides the desired fire resistance time, taking into account the carbonization rate of the wooden portion 20, the deck plate main body 10a will be hardly affected by heat until the wooden portion 20 burns out.
The wooden members 20 are arranged along the longitudinal direction L and the transverse direction W so as to cover the underside of the deck plate main body 10a exposed to the floor directly below, and are fixed to the deck plate main body 10a while abutting against the valley portions 13 of the deck plate main body 10a. Therefore, as shown in Figure 4, a gap is formed between the crests 11 of the deck plate main body 10a and the wooden members 20, forming a space S surrounded by the crests 11, the slopes 15, and the upper surface of the wooden members 20. This space S creates an air layer in the deck composite slab 1, further improving heat insulation.
The wood portion 20 can be made of any material as long as it is made of wood. However, since the carbonization rate differs depending on the type of wood, it is necessary to adjust the thickness of the wood portion 20 depending on the type of wood.
In this way, by utilizing the property of wood panels to provide a covering effect against heat during a fire until they are lost due to carbonization, the fire resistance (non-damageability, heat insulation) of the deck plate 10 and the composite deck slab 1 can be improved by providing the wooden section 20 on the underside of the deck plate 10. Furthermore, the thickness of the wooden section 20 can be determined based on the carbonization rate of the wood material constituting the wooden section 20 and the desired fire resistance time of the composite deck slab 1. This allows the wooden section 20 to be configured to an optimal thickness, ensuring neither excessive nor insufficient fire resistance, and enabling optimal function and cost selection. In other words, by optimizing the thickness of the wooden section 20, the wooden section 20 can be completely burned by the heat of a fire, preventing the wooden section 20 from finishing heating before it burns out, and preventing the wooden section 20 from turning into embers and continuing to burn after the fire is extinguished. Furthermore, the fire resistance (fire resistance time) of the composite deck slab 1 can be easily adjusted simply by adjusting the thickness of the wooden section 20.

The wooden portion 20 is provided on the deck plate main body 10a so as to expose the underside of the deck plate main body 10a in a partial area of the deck composite slab 1, on the underside of the deck plate main body 10a that is exposed to the floor directly below.
Specifically, the composite deck slab 1 is generally reinforced near the support beams B on which the deck plate 10 rests. In the reinforced area (reinforced region), the wooden portion 20 does not cover the deck plate main body 10a, leaving the underside of the deck plate main body 10a exposed. For example, as shown in Figures 1, 3, and 4, the wooden portion 20 is located at a predetermined distance from the support beams B at its longitudinal end. That is, the wooden portion 20 is not provided in any region near the longitudinal end of the deck plate 10 other than the region that rests on the support beams B, and the longitudinal end of the wooden portion 20 faces the flanges of the support beams B at a distance. Therefore, the length of the wooden portion 20 along the longitudinal direction of the deck plate 10 is formed to be shorter than the distance between the support beams B across which the deck plate 10 is spanned. As a result, from the end of the wooden part 20 along the longitudinal direction of the deck plate 10 to the flange of the support beam B, the deck plate main body 10a is not covered by the wooden part 20, and the underside of the deck plate main body 10a is exposed to the floor directly below.
For example, on the underside (the side where the wooden part 20 is installed) of the deck composite slab 1 that constitutes the floor, the area where other finishing components such as partition walls (wall materials) and decorative finishes for beams will be attached can be reinforced, and the wooden part 20 can be left out of that area, with the area other than that covered by the wooden part 20.

(Concrete section)
The concrete portion 60 is formed by solidifying concrete poured on the deck plate 10. Reinforcement members 61 for reinforcing the deck composite slab 1 may be provided inside the concrete portion 60.
Examples of the reinforcing member 61 include, as shown in Figures 1, 3, and 4, studs 62 joined to the flange of the support beam B so as to stand along the height direction H, welded wire mesh 63 that prevents cracks in the concrete section 60, reinforcing bars (not shown), reinforcing steel plates (not shown), etc.
The studs 62 are arranged in the short direction W on the flanges of the support beams B. The welded wire meshes 63 are spaced apart in the height direction (vertical direction) from the top surface of the deck plate 10 (deck plate main body 10a) and are provided along the surface direction of the peak portions 11.
By providing the studs 62 on the support beam B, the integration between the studs 62 and the concrete portion 60 can be increased in addition to the deck plate 10, and the deck composite slab 1 around the support beam B can be reinforced.
In addition, a plurality of studs 62 are provided on the flange of the support beam B along the extending direction of the flange, but this is not limited to studs 62 and may be achieved by burn-out plug welding or the like.

Such reinforcing members 61 improve the pull-out resistance 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 at the ends of the composite deck slab 1, thereby increasing the allowable performance of the live load, span, etc. In other words, the stress generated around the studs 62 can be dispersed to reinforce the ends of the composite deck slab 1, thereby improving fire resistance.
In the above-mentioned reinforcing members 61, the reinforcing bars and reinforcing steel plates arranged around the studs 62 and support beams B can reinforce the ends of the composite deck slab 1 (near the support beams B), while the welded wire mesh 63 arranged throughout the concrete section 60 and the reinforcing bars and reinforcing steel plates provided at any location can reinforce areas other than the ends of the composite deck slab 1 (such as the center of the composite deck slab 1). By not providing wood 20 in the areas reinforced by these reinforcing members 61, these reinforced areas are made to have fire-resistant weaknesses.
Furthermore, depending on the size, load capacity, etc. of the deck composite slab 1, the deck composite slab 1 may be reinforced using any one reinforcing member 61, or multiple reinforcing members 61 may be combined to reinforce the deck composite slab 1.

Here, we will explain the range of the underside of the deck plate main body 10a that is not covered by the wooden portion 20 relative to the reinforced region of the deck composite slab 1. Figure 6 is a table explaining the relationship between the reinforced region of the deck composite slab 1 and the range that is not covered by the wooden portion 20. Figure 7 is a table explaining the relationship between the reinforced region of the deck composite slab 1 and the range that is not covered by the wooden portion 20 when the length Lx in the short direction of the deck composite slab 1 is the standard length of 3600 mm.
The range in which negative bending acts near the support beam B is 1/4 of the short-side length Lx of the deck composite slab 1. In this case, the range in which negative bending acts is 3600 mm/4 = 900 mm, and structural reinforcement against negative bending is often provided near the support beam B within a range of 900 mm (simpler, about 1000 mm) from the support beam B. Here, in the case of reinforcement aimed solely at preventing crack expansion, reinforcement is often provided within a range of about half the above, that is, (Lx/4)/2 = 3600 mm/4/2 = 450 mm (simpler, about 500 mm) from the support beam B.

Therefore, as shown in Figures 6 and 7, if there is no reinforcement near the support beam B of the deck composite slab 1, the distance from the flange of the support beam B to the end of the wooden part 20 (the exposed length of the deck plate main body 10a) is in the range of 0 to 150 mm.
Furthermore, if reinforcement to prevent cracks from spreading in the concrete section 60 is performed near the support beams B of the composite deck slab 1, then the distance from the flange of the support beam B to the end of the wooden section 20 (the exposed length of the deck plate main body 10a) should be in the range of 150 to (Lx/4)/2 mm, where Lx is the short-side length of the composite deck slab 1. As shown in Figure 7, if the short-side length Lx of the composite deck slab 1 is 3600 mm, the distance from the flange of the support beam B to the end of the wooden section 20 (the exposed length of the deck plate main body 10a) should be in the range of 150 to 450 mm (approximately 150 to 500 mm for simplicity's sake).
Furthermore, if structural reinforcement against negative bending is performed near the support beams B of the composite deck slab 1, then, assuming that the length of the composite deck slab 1 in the short direction is Lx, the distance from the flange of the support beam B to the end of the wooden section 20 (the exposed length of the deck plate main body 10a) should be in the range of 450 to (Lx/4) mm. As shown in Figure 7, if the length Lx of the composite deck slab 1 in the short direction is 3600 mm, the distance from the flange of the support beam B to the end of the wooden section 20 (the exposed length of the deck plate main body 10a) should be in the range of 450 to 900 mm (approximately 500 to 1000 mm for simplicity's sake).

The deck plate 10 and composite deck slab 1 described above utilize the wood's ability to provide a protective barrier against heat generated during a fire until it is charred and consumed. By providing the wooden section 20 on the underside of the deck plate 10, the fire resistance (non-damageability, heat-insulating properties) of the deck plate 10 and composite deck slab 1 can be enhanced. Furthermore, the thickness of the wooden section 20 can be determined based on the char rate of the wood material comprising the wooden section 20 and the desired fire resistance time of the deck plate 10. This allows the wooden section 20 to be constructed to an optimal thickness, ensuring neither excessive nor insufficient fire resistance, and enabling optimal functionality and cost selection. In other words, by optimizing the wooden section 20 thickness, the wooden section 20 can be completely burned by the heat of a fire. The wooden section 20 does not finish heating before it burns out, and the wooden section 20 does not turn into embers and continue to burn after the fire is extinguished. Furthermore, the fire resistance (fire resistance time) of the composite deck slab 1 can be easily adjusted simply by adjusting the thickness of the wooden section 20.

Generally, since it is easier and more common to reinforce the area near the support beams B than the center of the composite deck slab 1, the center of the unreinforced composite deck slab 1 is a weak point. If a fire-resistant coating (wooden part 20) is provided on the entire underside of the deck plate 10, the weak point will remain the center of the composite deck slab 1, but if the area near the support beams B where reinforcement is performed is not coated, the weak point in terms of fire resistance will be the area near the support beams B.
Therefore, depending on the specifications of the reinforcement applied to the composite deck slab 1, a predetermined length from the flange of the support beam B is left without the wooden portion 20, leaving the underside of the deck plate main body 10a exposed. As a result, if the finishing members (decorative materials) are burned in the event of a fire, the deck plate main body 10a will be heated intensively in the area near the support beam B where there is no wooden portion 20, causing buckling and causing the deck plate 10 to peel off from the concrete portion 60. In a composite deck slab 1 in which the deck plate 10 and concrete portion 60 do not peel off and the composite effect is maintained, even if the deck plate 10 peels off from the concrete portion 60 in a narrow area of the reinforced region, the reduction in the structural strength of the composite deck slab 1 can be minimized.
After the wooden portion 20 disappears, thermal expansion is concentrated in the buckled area, and that expansion can be absorbed. In other words, in the area where the deck plate 10 has buckled after peeling off from the concrete portion 60, the thermal expansion of the deck plate 10, which is an unnecessary additional force, can be absorbed without damaging the deck composite slab 1. Therefore, no thermal expansion occurs in the area of the deck plate 10 where the wooden portion 20 was located, and the wide area is not damaged by the thermal expansion.

In this way, even if the area near the support beam B is designated as a weak point in the composite deck slab 1, because the area near the support beam B is reinforced, it will not become a weak point that would immediately lead to the collapse of the composite deck slab 1. Furthermore, depending on the design conditions, the area near the support beam B is unlikely to collapse immediately even without reinforcement. In other words, by intentionally not covering the deck plate main body 10a near the support beam B, the thermal expansion of the deck plate 10 can be concentrated near the support beam B, inducing the separation of the deck plate 10. Then, after the fire progresses and all of the wooden parts 20 are burned out, the entire surface of the deck plate 10 heats up as with a normal composite deck slab. However, by this time, the deck plate 10, which has already separated from the concrete portion 60 near the support beam B, absorbs the thermal expansion, preventing widespread damage to the composite deck slab 1.
Therefore, with the composite deck slab 1, damage caused by thermal expansion of the deck plate 10 that would accumulate near the center of a normal composite deck slab can be eliminated by thermal expansion near the high-strength support beams B, significantly improving the fire resistance of the composite deck slab 1. Furthermore, the increased costs of various reinforcements applied to a normal composite deck slab can be offset and reduced by minimizing the coverage area.

Furthermore, since the wooden section 20 functions as a decorative finishing material that hides the underside of the deck plate main body 10a, simply by providing the wooden section 20 on the deck plate 10, the deck composite slab 1 can be given the function of fire-resistant coating that blocks heat input to the deck plate 10 and the function of decorative finishing.This simplifies the processing applied to the deck plate 10 while improving the fire resistance of the deck plate 10 and the deck composite slab 1, for example, making it possible to omit fire-resistant reinforcing bars even when they are needed, and further improving multiple functions and performance such as appearance.
Here, multiple functions include, for example, improved in-plane shear strength, and deck plates and composite deck slabs have the function of bearing in-plane shear forces caused by earthquakes and wind, but the presence of the wooden section 20 can improve this function, so the strength of the deck plate or composite deck slab can be improved without changing its configuration. On the other hand, if performance equivalent to that of a deck plate or composite deck slab without the wooden section 20 is required, the presence of the wooden section 20 can simplify the configuration of the deck plate or composite deck slab, such as the deck plate height and plate thickness, the concrete volume and strength, and increase the slab span and load.
The other multiple functions include, for example, improved structural performance, and the presence of the wooden portion 20 can improve the vertical load support function when constructing the deck plate and when the composite deck slab, composite deck slab, or structural deck slab is completed. On the other hand, if performance equivalent to that of a deck plate or composite deck slab without the wooden portion 20 is required, the presence of the wooden portion 20 can simplify the configuration of the deck plate or composite deck slab, such as the height and thickness of the deck plate, the volume and strength of the concrete, or increase the span and load of the slab.
Furthermore, simply by precasting the wooden parts 20 in the valley parts 13 of the deck plate main body 10a, it is possible to finish the design of the deck plate 10 and add fire resistance to the deck composite slab 1, so that the floor slab and ceiling finish can be completed at the same time by simply pouring concrete on the top surface of the deck plate 10 on site.
Furthermore, by subjecting the wooden part 20 to a fireproofing treatment that adds fire resistance for a predetermined period of time, the thickness of the wooden part 20 required for the required fire resistance can be reduced.
Furthermore, by providing the deck plate 10 with fire resistance for a predetermined period of time, the thickness of the wooden portion 20 required for the required fire resistance can be reduced.
Furthermore, because a space S is formed between the underside of the deck plate main body 10a and the wood 20, an air layer can be formed in the deck composite slab 1, improving heat insulation and suppressing heat transfer to the upper surface (directly above) of the deck composite slab 1. This lengthens the time it takes for the temperature to reach the ignition temperature of combustible materials on the directly above floor.
The wooden members 20 are not limited to wood, but may be materials that improve multiple functions and performance, such as fire resistance and appearance, such as boards, panels, or sheets, such as wood wool cement boards or gypsum boards. Furthermore, when the wooden members 20 are formed as widthwise units, their width may be the same as, or larger or smaller than, the width of the deck plate 10. Furthermore, the joints between the wooden members 20 and the fitting portions between the deck plates 10 may or may not coincide.

<Non-damaging evaluation>
Figure 8 is a graph comparing the amount of deflection of a composite deck slab without wood 20 and a composite deck slab 1 with wood 20 when heated, with the horizontal axis representing heating time and the vertical axis representing displacement of the composite deck slab. In other words, Figure 8 evaluates the non-damageability of the composite deck slab. In the graph of Figure 8, the dashed line represents the composite deck slab without wood 20, and the solid line represents the composite deck slab 1 with wood 20.
As shown in Figure 8, the displacement of both deck composite slabs gradually increases until 60 minutes after heating is completed, but it can be seen that the deck composite slab 1 with the wooden part 20 is less likely to displace. It can be seen that the deck composite slab 1 with the wooden part 20 is less likely to displace at any time during heating and after heating is completed. Therefore, it can be seen that the deck composite slab 1 with the wooden part 20 is less likely to warp or be damaged by the effects of heat in the event of a fire.

<Evaluation of heat insulation properties>
Figure 9 is a graph comparing the temperature of the top surface of a composite deck slab without wood 20 and a composite deck slab 1 with wood 20 when heated, with the horizontal axis representing heating time and the vertical axis representing the temperature of the top surface of the composite deck slab. In other words, Figure 9 evaluates the heat-shielding properties of the composite deck slab. In the graph of Figure 9, the dashed line represents the composite deck slab without wood 20, and the solid line represents the composite deck slab 1 with wood 20.
As shown in Figure 9, as the heating time increases, the temperature of the top surface of both deck composite slabs rises, but it can be seen that the temperature of the top surface of deck composite slab 1 equipped with wooden members 20 rises less. It can be seen that the temperature of the top surface of deck composite slab equipped with wooden members 20 is kept lower at all times. Therefore, it can be seen that the temperature of the top surface of deck composite slab 1 equipped with wooden members 20 rises less in the event of a fire, and that it has higher heat insulation properties. In other words, it can be seen that the inclusion of wooden members 20 reduces the impact on the floor directly above in the event of a fire.

<Others>
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, if the vicinity of the center of the composite deck slab 1 is reinforced, the vicinity of the center may be left uncovered by the wooden section 20. In essence, in the composite deck slab 1, only the reinforced area or the area that is stronger than the others may be left uncovered by the wooden section 20 within a predetermined range in accordance with the reinforcement specifications, so that the strong area may be a weak point in terms of fire resistance.
Furthermore, the reinforcement specifications are not limited to those described above, and the extent to which the underside of the deck plate main body 10a is not covered by the wooden portion 20 can be set according to each specification.

REFERENCE SIGNS LIST 1 deck composite slab 10 deck plate 10a deck plate main body 11 peak portion 12 groove 13 valley portion 14 convex portion 15 inclined portion 16 engagement portion 17 bulge portion 18 groove 20 wood portion 60 concrete portion 61 reinforcing member 62 stud 63 welded wire mesh S space

Claims (8)

A deck composite slab comprising a deck plate placed on a support beam and a concrete portion poured on an upper surface of the deck plate,
A composite deck slab characterized by having a wooden portion provided on the underside of the deck plate main body portion so as to expose the underside of the deck plate main body portion in the reinforced area of the composite deck slab. A composite deck slab as described in claim 1, characterized in that the reinforced area is near the support beam on which the deck plate rests. A composite deck slab as described in claim 2, characterized in that the longitudinal ends of the deck plate main body in the area not resting on the support beam are exposed by a predetermined distance. 2. The composite deck slab according to claim 1, wherein the wooden portion is provided at a position on the underside of the deck plate body excluding a mounting position for a wall material . A composite deck slab as described in claim 1, characterized in that it is provided with reinforcing members that reinforce the concrete portion. A deck plate used in a deck composite slab,
A wooden part is provided on the underside of the deck plate,
The deck plate is characterized in that the wooden portion is arranged so as to expose the underside of the deck plate body in the reinforcement area of the deck composite slab that will be reinforced when concrete is poured onto the upper surface of the deck plate to construct the deck composite slab. The deck plate described in claim 6, characterized in that the reinforced area is near the support beam on which the deck plate rests. A deck plate as described in claim 6 or 7, characterized in that the wooden portion is formed from a decorative finishing material.