JP2023108774A - Deck composite slab, and concrete thickening method for deck composite slab - Google Patents

Abstract

To provide a deck composite slab which can be provided as a floor slab that requires having a performance of resisting fire for more than 2 hours in performance-based fireproof-design buildings, and its concrete thickening method.SOLUTION: A concrete 304 has a thickness greater than 100 mm on top of a crest part 3a of a deck plate 3. Thereby, a deck composite slab 300 can improve fireproof performance through thickening of thickness of the concrete 304 so as to meet a required performance of resisting fire for more than 2 hours in a performance-based fireproof-design building. As a result, for example, additionally placing the concrete on an existing slab enables minor work to cope with a tenant change to applications with a required time of resisting fire for more than 2 hours.SELECTED DRAWING: Figure 2

Description

The present invention relates to a composite deck slab and a method of thickening concrete for a composite deck slab.

As a conventional deck composite slab, one described in Patent Document 1 is known. The deck composite slab comprises a deck plate and concrete poured onto the deck plate.

Japanese Patent Application Laid-Open No. 2020-41348

Here, among the fireproof design routes defined by the Building Standards Act, the deck composite slab generally adopts the specification-based route A (see FIG. 3). On the other hand, Route C, which is a performance-based type, requires advanced design know-how, but it is possible to optimize the design because it evaluates the required fireproof performance and the available performance for each room, and it is effective in reducing costs in large-scale properties. is high.

Deck composite slabs differ in required performance depending on the design route (see, for example, FIG. 4). Specifically, in the fire-resistant design of route A, the required fire-resistant time of the floor is determined according to the number of floors, but the required fire-resistant time is 2 hours at the maximum. The heat shielding property is 1.2 hours (72 minutes), which is obtained by multiplying 1 hour by a safety factor of 1.2. On the other hand, in route C fire resistance design, the required performance is determined by the amount of heat generated and the amount of heat entering, so there are cases where fire resistance performance (including heat insulation) for more than 2 hours is required. In response to such a request, a configuration in which fire-resistant reinforcing bars are installed in the concrete of the deck composite slab is sometimes adopted. However, although this fire-resistant reinforcing bar has the effect of suppressing deformation, it is not effective in improving heat insulation, so there was a problem that it was difficult to ensure fire-resistant performance for more than two hours with conventional deck synthetic slabs.

In addition, in a building designed by Route C, if there is a change in the use of a room such as a tenant change, the required fire resistance time will increase because the preconditions will change from those at the time of design. , fire resistance times greater than 2 hours may be required.

The present invention has been made to solve such problems, and a composite deck slab that can be provided as a floor slab that requires fire resistance performance exceeding 2 hours in a performance-specific fire-resistant design building, and its It is an object of the present invention to provide a concrete thickening method for deck composite slabs.

The deck composite slab according to the present invention is a deck composite slab that is provided as a floor slab that requires fire resistance performance exceeding 2 hours in a performance-specific fire-resistant design building, and comprises a deck plate and a deck plate. and concrete laid down, wherein the thickness of the concrete on the crest of the deck plate is greater than 100 mm.

A composite deck slab according to the present invention comprises a deck plate and concrete poured onto the deck plate. Of these, the concrete has a thickness greater than 100 mm on the peaks of the deck plate. As a result, the composite deck slab improves fire resistance by increasing the thickness of the concrete sufficiently, and can meet the fire resistance requirement of more than 2 hours in fire resistance design buildings with advanced fire resistance verification. As a result, for example, by adding concrete to the existing slab, it is possible to cope with a tenant change to a use that exceeds the required fire resistance time of 2 hours with a minor construction work.

Refractory reinforcement may be placed within the concrete. In this case, the refractory reinforcing bars can restrain deformation of the composite deck slab.

The refractory reinforcement may be placed at a height greater than 40mm undercover. In this case, it is possible to reinforce the refractory reinforcing bar at an appropriate height position.

The thickness of the concrete on the ridges of the deck plate may be 115 mm or more. In this case, the fire resistance can be further improved.

In deck composite slabs, the required fire resistance time has increased due to a change in the use of the room due to a change in tenant, etc., and the thickness of the concrete may be increased by placing the concrete again. In this case, a change in use of the room can be accommodated with a minor construction work.

In the composite deck slab, the required fire resistance time is more than 2 hours, and the concrete thickness exceeds the safe range for construction in comparison of the casting load and the formwork performance of the deck plate in one casting. Concrete placement may be divided into two or more times. In this case, the thickness of the concrete can be increased while ensuring safety in construction.

The concrete thickening method for a deck composite slab according to the present invention is a concrete thickening method for a deck composite slab that is provided as a floor slab that requires fire resistance performance exceeding 2 hours in a fire-resistant design building with advanced fire resistance verification. By placing the crack expansion prevention bars directly on the existing concrete for the deck plate and the deck composite slab with concrete placed on the deck plate, and placing the concrete again, the concrete Increase thickness.

According to the concrete thickening method of the composite deck slab according to the present invention, it is possible to obtain the same functions and effects as those of the composite deck slab described above.

According to the present invention, it is possible to provide a deck composite slab that can be provided as a floor slab that requires fire resistance performance exceeding two hours in a performance-defined fireproof design building, and a method for increasing the concrete thickness of the deck composite slab.

1 is a schematic cross-sectional view of a composite deck slab according to a first embodiment of the invention; FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1; FIG. It is a figure which shows a fireproof design route. Fig. 3 is a table showing the main differences between Route A and Route C in deck composite slabs; It is a figure which shows a test method. It is a table showing test conditions. It is a table|surface which shows the measurement result of the temperature detection sensor of a peak part, and the temperature detection sensor of a valley part, and is for heat-shielding evaluation. It is a table|surface which shows the measurement result of a deflection amount detection sensor, and performs non-damaging evaluation. FIG. 5 is a cross-sectional view for explaining a deck composite slab according to a second embodiment of the present invention and a concrete thickening method for manufacturing the deck composite slab. It is a table showing test conditions. It is a table|surface which shows the measurement result of the temperature detection sensor of a peak part, and the temperature detection sensor of a valley part, and is for heat-shielding evaluation. It is a table|surface which shows the measurement result of a deflection amount detection sensor, and performs non-damaging evaluation. It is a sectional view showing a deck plate concerning a modification.

Preferred embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic cross-sectional view of a composite deck slab 100 according to a first embodiment of the invention. FIG. 2 is a cross-sectional view taken along line II--II of FIG. The deck composite slab 100 is provided as a floor slab in performance-defined (high fire-rated) fire-resistant design buildings where fire-resistant performance in excess of 2 hours is required.

Here, the fireproof design route will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a diagram showing a fireproof design route. FIG. 3 is a diagram defined in the "Guidebook for Fire Resistance of Structural Materials (Architectural Institute of Japan)". Of the fireproof design routes defined by the Building Standards Act, the deck composite slab 100 generally adopts the specification-based route A. On the other hand, Route C, which is a performance-based type, requires advanced design know-how, but it is possible to optimize the design because it evaluates the required fireproof performance and the available performance for each room, and it is effective in reducing costs in large-scale properties. is high. The main differences between Route A and Route C in deck composite slab 100 are shown in the table of FIG.

Regarding fireproof performance, in the fireproof performance confirmation test shown in Fig. 5, the heat shielding property and non-damaging property are evaluated based on the "fireproof performance test and evaluation work method manual". The heat shielding property is evaluated by the temperature rise of the back surface (upper surface) of the synthetic deck slab 100 . Non-damageability is evaluated by the deflection amount BA of the composite deck slab 100 . As shown in FIG. 5(a), a specimen of the composite deck slab 100 is placed on a refractory furnace 101, a constant load is applied to the upper surface, and the temperature rise and deflection amount BA are measured. Further details of the test will be described later.

As shown in FIG. 4, the required performance varies depending on the design route. Specifically, in the fire-resistant design of route A, the required fire-resistant time of the floor is determined according to the number of floors, but the required fire-resistant time is 2 hours at the maximum. The heat shielding property is 1.2 hours (72 minutes), which is obtained by multiplying 1 hour by a safety factor of 1.2. On the other hand, in route C fire resistance design, the required performance is determined by the amount of heat generated and the amount of heat entering, so there are cases where fire resistance performance (including heat insulation) for more than 2 hours is required.

Here, as a comparative example, a composite deck slab 200 having fire-resistant reinforcing bars 5 as shown in FIG. 2(b) is provided. Although the fire-resistant reinforcing bars 5 have the effect of suppressing deformation, they do not have the effect of improving heat insulation, so it is difficult to ensure the fire-resistant performance of the deck composite slab 200 according to the comparative example for more than two hours.

As described above, in the fire-resistant design according to Route C, there are cases where fire-resistant performance exceeding 2 hours is required, and improvement in heat-shielding performance cannot be expected only with the fire-resistant reinforcing bars of the composite deck slab 200 according to the comparative example. In addition, if the concrete thickness is increased, the weight of the slab will increase, which may affect other members, such as increasing the size of columns and beams and increasing the number of small beams.

On the other hand, the composite deck slab 100 according to the present embodiment is provided as a floor slab that requires fire resistance performance exceeding 2 hours in a fire resistance design building with advanced fire resistance verification (Route C). Specifically, deck composite slab 100 comprises deck plate 3 , concrete 4 and rock wool 6 . A deck composite slab 100 is supported by a pair of beams 2 .

As shown in FIG. 2A, the deck plate 3 alternately has peaks 3a and valleys 3b in the width direction D2. The peak portion 3a is provided so as to protrude upward from the bottom surface of the valley portion 3b. The plurality of peaks 3a extend parallel to each other in the span direction D1 while being separated from each other in the width direction D2. The peak portion 3a constitutes both side walls of the valley portion 3b.

Concrete 4 is placed on deck plate 3 . Concrete 4 is filled in valleys 3b of deck plate 3 to a position higher than the upper surface of peaks 3a. Thereby, the concrete 4 has an upper surface extending in the span direction D1 and the width direction D2 above the deck plate 3 . The upper surface becomes the upper surface 100 a of the composite deck slab 100 . The thickness t of the concrete 4 on the ridges 3a of the deck plate 3 is 50 mm to 100 mm.

A crack expansion prevention bar 7 is arranged inside the concrete 4. - 特許庁The crack-enhancement prevention streaks 7 are net members extending parallel to the span direction D1 and the width direction D2. The crack expansion preventing line 7 is arranged between the peak portion 3a and the upper surface 100a.

Rock wool 6 is a member that covers deck plate 3 . The rock wool 6 is formed by blowing rock wool granules onto the lower surface 3c of the deck plate 3. As shown in FIG. The rock wool 6 is formed over the entire lower surface 3c of the deck plate 3 with a predetermined thickness according to the uneven shape of the lower surface 3c. The rock wool 6 coating thickness is greater than 20 mm and may be 25 mm or more. Moreover, the coating thickness of the rock wool 6 may be 65 mm or less. However, since the bottom surface is sprayed, the thickness of the coating should preferably be 25 mm or more and 35 mm or less from the viewpoint of avoiding falling off.

The performance of deck composite slab 100 will now be described with reference to FIGS. FIG. 5 is a diagram showing the test method. FIG. 6 is a table showing test conditions for Example 1 and Comparative Example. First, as shown in FIG. 5(b), the dimension L1 of the support span in the span direction D1 of the composite deck slab 100 relating to the specimen is 3600 mm, and the dimension W1 in the width direction D2 is 2000 mm. In the deck plate of the composite deck slab 100, the pitch between peaks in the width direction D2 is 300 mm. Further, valleys are arranged at the ends of the deck plate of the composite deck slab 100 in the width direction D2. The dimension W2 between the center of the first peak from the end 100b in the width direction D2 of the composite deck slab 100 and the end of the deck plate 3 is 250 mm. As shown in FIG. 5B, the upper surface 100a of the composite deck slab 100 is provided with temperature detection sensors 102A and 102B and a deflection amount detection sensor 103. As shown in FIG. A dimension L2 from the supporting point on one side of the temperature detection sensors 102A and 102B in the span direction D1 is 900 mm. The temperature detection sensor 102A is provided at the center position of the first mountain portion from the end portion 100b, and the dimension W2 in the width direction D2 from the end portion 100b is 250 mm. The temperature detection sensor 102B is provided at the center position of the second valley from the end 100c, and the dimension W3 in the width direction D2 from the end 100c is 400 mm. The deflection amount detection sensor 103 is arranged at the center position of the composite deck slab 100, and the dimension L4 in the span direction D1 from the supporting point is 1800 mm. A dimension W4 in the width direction D2 from the end portion 100b is 1000 mm. Other conditions are shown in FIG. The specimen according to the comparative example is designated as "No. 1", and the specimen according to Example 1 is designated as "No. 2". In addition, heating is completed in 2 hours (120 minutes) for "No. 1" according to the comparative example, and heating is completed in 3 hours (180 minutes) for "No. 2" according to Example 1. .

FIG. 7 is a table showing the measurement results of the peak temperature detection sensor 102A and the valley temperature detection sensor 102B, and for evaluating heat shielding properties. As shown in FIG. 7, the temperature of the upper surface 100a was compared with the comparative example "No. It can be confirmed that the temperature rise is more gradual in the .2 rock wool coating specification, and that the temperature is below the specified value even at the point of 3 hours (180 minutes) of heating.

FIG. 8 is a table showing measurement results of the deflection amount detection sensor 103 for non-damaging evaluation. As shown in FIG. 8, the amount of deflection is also compared with the "No. 1 fireproof reinforcing bar specification" according to the comparative example, and the "No. 2 rock wool covering specification" according to Example 1 has a greater amount of deflection. It can be confirmed that the increase is gradual, and the temperature is below the specified value even after heating for 3 hours. "No. 2 Rock Wool Coating Specification" according to Example 1 is covered with rock wool, so that the decrease in strength and the decrease in Young's modulus of concrete due to the temperature rise of the deck plate can be delayed.

Next, functions and effects of the composite deck slab 100 according to this embodiment will be described.

The deck composite slab 100 according to this embodiment includes a deck plate 3 , concrete 4 placed on the deck plate 3 , and rock wool 6 covering the deck plate 3 . As a result, the deck synthetic slab 100 can protect the heating surface (lower surface 3c) of the deck plate 3 with the rock wool 6, so that the fire resistance performance is improved, and it can be used for 2 hours in a performance-specific fire-resistant design building. Can meet the requirements of fire resistance performance exceeding. As a result, it is possible to design more economically than before by using it for fire-resistant design for advanced fire-resistant performance verification (Route C).

The coating thickness of rock wool 6 may be greater than 20 mm. In this case, the rock wool 6 can exhibit sufficient fire resistance.

The coating thickness of the rock wool 6 may be 25 mm or more and 35 mm or less. In this case, it is possible to further improve the fire resistance and prevent the rock wool 6 from coming off.

The rock wool 6 may have a shape corresponding to the lower surface 3 c of the deck plate 3 . In this embodiment, since the lower surface 3c of the deck plate 3 has an uneven shape, the rock wool 6 also has an uneven shape. In this case, the coating thickness of the rock wool 6 can be set to an appropriate thickness according to the shape of the lower surface 3c of the deck plate 3.

The method for improving the fire resistance performance of the deck composite slab 100 according to the present embodiment is a deck composite slab 100 that is provided as a floor slab that requires fire resistance performance exceeding 2 hours in a fire resistance design building in performance-specific fire resistance verification. In the method for improving fire resistance performance by spraying rock wool, the deck synthetic slab 100 including the deck plate 3 and the concrete 4 placed on the deck plate 3 is coated with the sprayed rock wool on the lower surface 3c of the deck plate 3. conduct.

According to the method for improving the fire resistance performance of the synthetic deck slab 100 according to the present embodiment, it is possible to obtain the same functions and effects as those of the synthetic deck slab 100 described above.

[Second embodiment]
FIG. 9 is a cross-sectional view for explaining a deck composite slab 300 according to a second embodiment of the present invention and a concrete thickening method for manufacturing the deck composite slab 300. FIG. The composite deck slab 300 shown in FIG. 9(c) is provided as a floor slab that requires a fire resistance performance exceeding 2 hours in a performance-specific fire-resistant design building. Deck composite slab 300 comprises concrete 304 that is thicker than concrete 4 of deck composite slab 100 shown in FIG. The thickness t2 of the concrete 304 on the ridges 3a of the deck plate 3 may be greater than 100 mm and 115 mm or more. Note that the thickness t2 of the concrete 304 may be 150 mm or less.

In the concrete 304, the refractory reinforcing bars 5 are arranged at the positions of the valleys 3b. The fireproof reinforcing bar 5 extends in the span direction D1 at a substantially central position in the internal space of the valley portion 3b. The refractory reinforcing bars 5 are arranged at a height exceeding 40 mm for the undercover. The dimension of the undercover is the height dimension from the bottom surface of the valley portion 3b.

Inside the concrete 304, a crack expansion prevention bar 8 is arranged. The crack expansion prevention bar 8 is arranged above the crack expansion prevention bar 7. - 特許庁The crack expansion prevention bar 7 is arranged at the position of the upper surface 100a of the concrete 4 before thickening.

A concrete thickening method for the deck composite slab 300 will be described. This method is performed on an existing composite deck slab 200 shown in FIG. 9(a). First, as shown in FIG. 9B, the crack expansion prevention bars 8 are directly arranged on the existing concrete 4 for the composite deck slab 200 . The crack expansion prevention bar 8 is directly arranged on the upper surface 100 a of the existing concrete 4 . The thickness of the concrete 304 is increased by placing the concrete 304a again. Here, additional concrete 304a is placed on the upper surface 100a of the existing concrete 4. As shown in FIG. This completes the deck composite slab 300 .

The performance of deck composite slab 300 will now be described with reference to FIGS. 10-12. The test conditions are the same as in the first embodiment except that Example 2 shown in FIG. 10 is used as the deck composite slab 300 test piece. The specimen according to the comparative example is designated as "No. 1", and the specimen according to Example 2 is designated as "No. 2". Note that the heating of "No. 1" according to the comparative example was completed in 2 hours (120 minutes), and the heating of "No. 2" according to Example 1 was completed in 231 minutes.

FIG. 11 is a table showing the measurement results of the peak temperature detection sensor 102A and the valley temperature detection sensor 102B, and for evaluating heat shielding properties. As shown in FIG. 11, compared with the comparative example "No. 1 80 mm specification", the "No. 2 115 mm specification" according to Example 2 has a thicker concrete, and the temperature rise is gentler. , and it can be confirmed that even if the heating exceeds 3 hours, it is below the specified value.

FIG. 12 is a table showing measurement results of the deflection amount detection sensor 103 for non-damaging evaluation. As shown in FIG. 12, the amount of deflection was slightly smaller in the "No. 2 115 mm specification" up to 2 hours of heating compared to the "No. 1 80 mm specification" of the comparative example, but After that, the rigidity is stable even after heating for more than 3 hours, and it can be confirmed that it has fire resistance performance for more than 3 hours.

Actions and effects of the composite deck slab 300 according to this embodiment will be described.

A composite deck slab 300 according to this embodiment includes a deck plate 3 and concrete 304 placed on the deck plate 3 . Of these, the concrete 304 has a thickness greater than 100 mm on the peaks 3 a of the deck plate 3 . As a result, the deck composite slab 300 can improve the fire resistance performance by sufficiently thickening the concrete 304, and can satisfy the fire resistance performance requirement for more than 2 hours in a performance-specific fire-resistant design building. As a result, for example, by adding concrete to the existing slab, it is possible to cope with a tenant change to a use that exceeds the required fire resistance time of 2 hours with a minor construction work.

Refractory reinforcing bars 5 may be placed within the concrete 304 . In this case, the refractory reinforcing bars 5 can suppress deformation of the composite deck slab 300 .

The refractory reinforcing bars 5 may be arranged at a height above 40 mm of the undercover. In this case, reinforcement by the fireproof reinforcement 5 can be performed at an appropriate height position.

The fireproof reinforcement 5 may be arranged at a height of 45 mm or more in the lower covering. In this case, by increasing the thickness of the concrete cover, the temperature rise of the fire-resistant reinforcement can be delayed, and the fire-resistant time can be lengthened.

The fireproof reinforcing bars 5 may be arranged at a height of 45 mm or more and 65 mm or less in the lower covering. In this case, the bending occurring at the tensile edge of the composite slab can be efficiently supported while the fire resistance time is lengthened, and the fire resistance performance can be further improved.

The thickness of the concrete 304 on the ridges 3a of the deck plate 3 may be 115 mm or more. In this case, the fire resistance can be further improved.

In the deck composite slab 1, the required fire resistance time has increased due to a change in the use of the room due to a change in tenant, etc., and the thickness of the concrete may be increased by placing the concrete again. In this case, a change in use of the room can be accommodated with a minor construction work.

In deck composite slab 1, the required fire resistance time is more than 2 hours, and the concrete thickness exceeds the safe range for construction in comparison of the casting load and the formwork performance of the deck plate in one casting. , may consist of two or more separate pours of concrete. In this case, the thickness of the concrete can be increased while ensuring safety in construction.

The method for increasing the concrete thickness of the deck composite slab 300 according to the present embodiment directly places the crack expansion prevention bars 8 on the existing concrete 4, and casts the concrete 304a again, thereby increasing the thickness of the concrete 304. . This makes it possible to obtain the same functions and effects as those of the composite deck slab 300 described above.

The invention is not limited to the embodiments described above.

For example, the shape of the deck plate may be changed as appropriate without departing from the gist of the present invention. For example, a deck plate having a lower deck height than the deck plate shown in FIG. 2(a) may be employed. Specifically, like the deck plate 3 shown in FIG. 13C, the deck plate shown in FIG. For example, a deck plate having a higher deck height than the deck plate shown in FIG. 2(a) may be employed. Specifically, like the deck plate 3 shown in FIG. 13(b), the height ratio to the standard shape may be 1.60. In addition, like the deck plate 3 shown in FIG. 13(a), a vertical rib type deck plate may be adopted as the deck plate, in which the ribs protrude upward from the substantially flat bottom surface. . Also, the reinforcing bars placed inside the concrete may be changed as appropriate.

3... deck plate, 4,304... concrete, 5... refractory reinforcement bar, 6... rock wool, 7, 8... crack expansion prevention bar, 100, 300... deck synthetic slab.

Claims (7)

A deck composite slab that is provided as a floor slab that requires fire resistance performance exceeding 2 hours in a fire-resistant design building in performance-based fire resistance verification,
deck plate and
Concrete placed on the deck plate,
A composite deck slab, wherein the thickness of the concrete on the peaks of the deck plate is greater than 100 mm. 2. The composite deck slab of claim 1, wherein refractory reinforcing bars are disposed within said concrete. 3. A deck composite slab according to claim 2, wherein said refractory reinforcement bars are located at a height greater than 40 mm undercover. A deck composite slab according to any one of claims 1 to 3, wherein the thickness of the concrete on the peaks of the deck plate is 115 mm or more. In the deck composite slab, the required fire resistance time has increased due to a change in the use of the room due to a change in tenant, etc., and the thickness of the concrete has been increased by placing the concrete again. A deck composite slab according to any preceding paragraph. In the deck composite slab, the required fire resistance time is more than 2 hours, and the concrete thickness exceeds the safe range for construction in comparison of the casting load and the formwork performance of the deck plate in one casting. A composite deck slab according to any one of claims 1 to 5, comprising two or more separate pours of concrete. A concrete thickening method for a deck synthetic slab provided as a floor slab that requires fire resistance performance exceeding 2 hours in a fire-resistant design building in performance-specific fire-resistant performance verification,
For a deck composite slab comprising a deck plate and concrete placed on the deck plate, the crack expansion prevention bars are directly placed on the existing concrete, and the concrete is placed again to reduce the thickness of the concrete. A concrete thickening method for deck composite slabs to increase .

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