Deck composite slab

Abstract

To provide a deck composite slab that can be offered as a floor slab requiring fire resistance exceeding 2 hours in performance-based fire-resistant design buildings, and a concrete thickening method for the same.SOLUTION: Concrete 304 has a thickness greater than 100 mm on a raised portion 3a of a deck plate 3. This allows a composite deck slab 300 to improve its fire resistance performance by sufficiently thickening the concrete 304, enabling it to meet the requirement for fire resistance exceeding 2 hours in performance-based fire-resistant design buildings. As a result, minor construction work can accommodate tenant changes for uses requiring fire resistance exceeding 2 hours, such as by adding concrete overlay to existing slabs.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A conventional composite deck slab is known from Patent Document 1. This composite deck slab includes a deck plate and concrete poured on the deck plate. [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, among the fire resistance design routes stipulated by the Building Standards Act, Route A, which is a specification-based route, is generally adopted for deck composite slabs (see Figure 3). On the other hand, Route C, which is a performance-based route, requires advanced design know-how, but allows for optimal design by evaluating the required and existing fire resistance performance on a room-by-room basis, and is highly effective in reducing costs for large-scale properties.

[0005] The required performance of composite deck slabs varies depending on the design route (see Figure 4, for example). Specifically, in the fire-resistance design of Route A, the required fire resistance time of each floor is determined by the number of floors, with a maximum of two hours. The required heat resistance is 1.2 hours (72 minutes), calculated by multiplying one hour by a safety factor of 1.2. On the other hand, in the fire-resistance design of Route C, the required performance is determined by factors such as heat generation and heat penetration, and in some cases, fire resistance (including heat resistance) of more than two hours is required. To meet such requirements, a design that installs fire-resistant reinforcement bars within the concrete of the composite deck slab is sometimes adopted. However, while this fire-resistant reinforcement bar is effective in suppressing deformation, it is not effective in improving heat resistance, making it difficult to achieve a fire resistance of more than two hours with conventional composite deck slabs.

[0006] In addition, in a building designed using Route C, if there is a change in the use of a room, such as a change in tenant, the assumptions will change from the time of design, and the required fire resistance time will increase, and areas that were initially able to meet a 2-hour fire resistance standard may be required to meet a fire resistance time of more than 2 hours.

[0007] The present invention has been made to solve such problems, and aims to provide a deck composite slab that can be used as a floor slab that requires a fire resistance performance of more than two hours in performance-specified fire-resistant buildings. [Means for solving the problem]

[0008] The composite deck slab of the present invention is a composite deck slab that is provided as a floor slab required to have a fire resistance performance of more than 2 hours in a fire-resistant designed building with a performance-defined fire resistance performance verification.The composite deck slab is used in a fire-resistant designed building with an advanced fire resistance performance verification (Route C), and comprises a deck plate and concrete poured on the deck plate, the thickness of the concrete on the crest of the deck plate is greater than 100 mm, and fire-resistant reinforcement is arranged in the concrete, with the fire-resistant reinforcement arranged at a height of 45 mm or more and 65 mm or less below the cover.

[0009] The thickness of the concrete on the crest of the deck plate may be 115 mm or more, which can further improve fire resistance.

[0010] In the case of a composite deck slab, if the required fire resistance time increases due to a change in the use of the room due to a tenant change or other reason, the concrete thickness can be increased by pouring the concrete again. In this case, the change in use of the room can be accommodated with minor construction work.

[0011] For composite deck slabs, if the required fire resistance time is more than two hours and a single pour would result in a concrete thickness that exceeds the safe range for construction, comparing the pouring load and the deck plate formwork performance, the concrete may be poured in two or more steps. In this case, the concrete thickness can be increased while ensuring construction safety. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a composite deck slab that can be used as a floor slab that requires a fire resistance performance of more than two hours in a performance-specified fire-resistant design building. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view of a deck composite slab according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 1 shows a fire-resistant design route. [Figure 4] This is a table showing the main differences between Route A and Route C for deck composite slabs. [Figure 5] FIG. 1 is a diagram showing a test method. [Figure 6] 1 is a table showing test conditions. [Figure 7] 10 is a table showing measurement results of the temperature detection sensors in the peak portions and the valley portions, for evaluating the heat insulating properties. [Figure 8]10 is a table showing the measurement results of the deflection amount detection sensor and used for performing a non-damage evaluation. [Figure 9] FIG. 10 is a cross-sectional view illustrating a deck composite slab according to a second embodiment of the present invention and a concrete thickness increasing method for manufacturing the deck composite slab. [Figure 10] 1 is a table showing test conditions. [Figure 11] 10 is a table showing measurement results of the temperature detection sensors in the peak portions and the valley portions, for evaluating the heat insulating properties. [Figure 12] 10 is a table showing the measurement results of the deflection amount detection sensor and used for performing a non-damage evaluation. [Figure 13] FIG. 10 is a cross-sectional view showing a deck plate according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0015] [First embodiment] Fig. 1 is a schematic cross-sectional view of a deck composite slab 100 according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. The deck composite slab 100 is used as a floor slab that is required to have a fire resistance performance of more than two hours in a performance-defined fire-resistant building (with advanced fire resistance performance verification).

[0016] Here, the fire resistance design route will be explained with reference to Figures 3 and 4. Figure 3 is a diagram showing the fire resistance design route. Figure 3 is a diagram specified in the "Fire Resistance Guidebook for Structural Materials (Architectural Institute of Japan)." Of the fire resistance design routes specified by the Building Standards Act, Route A, which is a specification-based route, is generally adopted for deck composite slabs 100. On the other hand, Route C, which is a performance-based route, requires advanced design know-how, but allows for optimal design by evaluating the required and existing fire resistance performance on a room-by-room basis, and is highly effective in reducing costs for large-scale buildings. The main differences between Route A and Route C for deck composite slabs 100 are shown in the table in Figure 4.

[0017] Regarding fire resistance, the heat insulation and non-damage performance are evaluated in the fire resistance confirmation test shown in Figure 5 based on the "Fire Resistance Testing and Evaluation Procedure Manual." Heat insulation is evaluated by the temperature rise on the back surface (top surface) of the composite deck slab 100. Non-damage performance is evaluated by the deflection amount BA of the composite deck slab 100. As shown in Figure 5(a), a test specimen of the composite deck slab 100 is placed on a fire-resistant furnace 101, a constant load is applied to the top surface, and the temperature rise and deflection amount BA are measured. Further details of the test will be described later.

[0018] As shown in Figure 4, the required performance differs depending on the design route. Specifically, in the fire resistance design for Route A, the required fire resistance time for each floor is determined according to the number of floors, with the maximum required fire resistance time being two hours. In addition, the required heat resistance is 1.2 hours (72 minutes), calculated by multiplying one hour by a safety factor of 1.2. On the other hand, in the fire resistance design for Route C, the required performance is determined by factors such as the amount of heat generated and the amount of heat entering, so in some cases fire resistance (including heat resistance) of more than two hours is required.

[0019] Here, as a comparative example, there is a composite deck slab 200 provided with fire-resistant reinforcement bars 5 as shown in Fig. 2(b). Although the fire-resistant reinforcement bars 5 are effective in suppressing deformation, they are not effective in improving heat insulation, so it is difficult to ensure fire resistance of more than two hours with the composite deck slab 200 according to the comparative example.

[0020] As described above, in the case of fire resistance design based on Route C, there are cases where fire resistance of more than two hours is required, and improvement in heat insulation performance cannot be expected only from the fire-resistant reinforcement of the deck composite slab 200 according to the comparative example. Furthermore, if the concrete thickness is increased, the weight of the slab will increase, which may have an impact on other components, such as increasing the size of columns and beams and the number of sub-beams.

[0021] In contrast, the composite deck slab 100 according to this embodiment is provided as a floor slab that requires a fire resistance performance of more than two hours in a fire-resistant design building with an advanced fire resistance performance verification (Route C). Specifically, the composite deck slab 100 includes a deck plate 3, concrete 4, and rock wool 6. The composite deck slab 100 is supported by a pair of beams 2.

[0022] As shown in FIG. 2(a), the deck plate 3 has alternating peaks 3a and valleys 3b in the width direction D2. The peaks 3a are provided so as to protrude upward from the bottom surfaces of the valleys 3b. The peaks 3a extend parallel to each other in the span direction D1 while being spaced apart from each other in the width direction D2. The peaks 3a form both side walls of the valleys 3b.

[0023] The concrete 4 is poured onto the deck plate 3. The concrete 4 is filled into the valleys 3b of the deck plate 3 up to a position higher than the top surfaces of the peaks 3a. As a result, the concrete 4 has an upper surface above the deck plate 3 that extends in the span direction D1 and width direction D2. This upper surface becomes the upper surface 100a of the deck composite slab 100. The thickness t of the concrete 4 on the peaks 3a of the deck plate 3 is 50 mm to 100 mm.

[0024] Crack expansion prevention bars 7 are arranged inside the concrete 4. The crack expansion prevention bars 7 are mesh members that extend parallel to the span direction D1 and width direction D2. The crack expansion prevention bars 7 are arranged between the ridges 3a and the upper surface 100a.

[0025] The rock wool 6 is a member that covers the deck plate 3. The rock wool 6 is formed by spraying granular rock wool onto the underside 3c of the deck plate 3. The rock wool 6 is formed over the entire underside 3c of the deck plate 3 to a predetermined thickness according to the uneven shape of the underside 3c of the deck plate 3. The coating thickness of the rock wool 6 may be greater than 20 mm and may be 25 mm or more. Alternatively, the coating thickness of the rock wool 6 may be 65 mm or less. However, because the rock wool 6 is sprayed onto the underside, it is desirable to keep the coating thickness between 25 mm and 35 mm to prevent it from falling off.

[0026] Next, the performance of the composite deck slab 100 will be described with reference to FIGS. 5 to 8. FIG. 5 is a diagram illustrating the test method. FIG. 6 is a table illustrating the test conditions for Example 1 and Comparative Example. First, as shown in FIG. 5(b), the support span dimension L1 in the span direction D1 of the composite deck slab 100 of the test 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 the crests in the width direction D2 is 300 mm. In addition, valleys are disposed at the end of the deck plate of the composite deck slab 100 in the width direction D2. The dimension W2 between the center of the first crest from the end 100b of the composite deck slab 100 in the width direction D2 and the end of the deck plate 3 is 250 mm. As shown in FIG. 5(b), temperature detection sensors 102A and 102B and a deflection detection sensor 103 are provided on the upper surface 100a of the composite deck slab 100. The dimension L2 of the temperature detection sensors 102A and 102B from the support point on one side in the span direction D1 is 900 mm. The temperature detection sensor 102A is installed at the center of the first peak from the end 100b, and the dimension W2 in the width direction D2 from the end 100b is 250 mm. The temperature detection sensor 102B is installed at the center 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 detection sensor 103 is located at the center of the deck composite slab 100, and the dimension L4 in the span direction D1 from the support point is 1800 mm. The dimension W4 in the width direction D2 from the end 100b is 1000 mm. Other conditions are shown in Figure 6. The test specimen for the comparative example is designated "No. 1," and the test specimen for Example 1 is designated "No. 2." For "No. 1" according to the comparative example, heating was completed after 2 hours (120 minutes), and for "No. 2" according to Example 1, heating was completed after 3 hours (180 minutes).

[0027] Fig. 7 is a table for evaluating heat insulation performance, showing the measurement results of the temperature detection sensors 102A and 102B in the peaks and valleys. As shown in Fig. 7, the temperature of the upper surface 100a of the "No. 2 rock wool coating specification" according to Example 1 rose more slowly than the "No. 1 fire-resistant reinforcement specification" of the comparative example, in which the deck plate is exposed on the heated surface (underside), and it can be confirmed that the temperature remained below the specified value even after 3 hours (180 minutes) of heating.

[0028] FIG. 8 shows the measurement results of the deflection detection sensor 103 and is a table for performing a non-damage evaluation. As shown in FIG. 8, the deflection also increases more slowly in the "No. 2 rock wool coating specification" of Example 1 compared to the "No. 1 fire-resistant reinforcement specification" of the comparative example, and it can be confirmed that the deflection remains below the specified value even after three hours of heating. Because the "No. 2 rock wool coating specification" of Example 1 is coated with rock wool, it is possible to delay the decrease in strength and the decrease in Young's modulus of concrete due to the increase in deck plate temperature.

[0029] Next, the operation and effect of the composite deck slab 100 according to this embodiment will be described.

[0030] The composite deck slab 100 according to this embodiment includes a deck plate 3, concrete 4 poured on the deck plate 3, and rock wool 6 covering the deck plate 3. This allows the composite deck slab 100 to protect the heated surface (underside 3c) of the deck plate 3 with the rock wool 6, improving fire resistance and enabling it to meet the fire resistance requirement of more than two hours in performance-based fire-resistant buildings. This allows it to be used in fire-resistant designs for advanced fire resistance verification (Route C), enabling more economical designs than before.

[0031] The coating thickness of the rock wool 6 may be greater than 20 mm. In this case, the rock wool 6 can exhibit sufficient fire resistance.

[0032] The coating thickness of the rock wool 6 may be 25 mm or more and 35 mm or less. In this case, the fire resistance performance can be further improved and the rock wool 6 can be prevented from falling off.

[0033] The rock wool 6 may have a shape that corresponds to the underside 3c of the deck plate 3. In this embodiment, since the underside 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 adjusted to an appropriate thickness in accordance with the shape of the underside 3c of the deck plate 3.

[0034] The method for improving the fire resistance of a deck composite slab 100 according to this embodiment is a method for improving the fire resistance of a deck composite slab 100, which is provided as a floor slab that is required to have a fire resistance performance of more than two hours in a fire-resistant design building that undergoes performance-defined fire resistance verification, by spraying rock wool, and for a deck composite slab 100 that comprises a deck plate 3 and concrete 4 poured on the deck plate 3, a sprayed rock wool coating is applied to the underside 3c of the deck plate 3.

[0035] According to the method for improving the fire resistance of the composite deck slab 100 according to this embodiment, it is possible to obtain the same functions and effects as those of the composite deck slab 100 described above.

[0036] Second Embodiment FIG. 9 is a cross-sectional view illustrating a composite deck slab 300 according to a second embodiment of the present invention and a concrete thickening method for manufacturing the composite deck slab 300. The composite deck slab 300 shown in FIG. 9(c) is provided as a floor slab required to have a fire resistance of more than two hours in a performance-based fire-resistant building. The composite deck slab 300 includes concrete 304 that is thicker than the concrete 4 of the composite deck slab 100 shown in FIG. 2. The thickness t2 of the concrete 304 on the peak portion 3a of the deck plate 3 is greater than 100 mm and may be 115 mm or greater. The thickness t2 of the concrete 304 may be 150 mm or less.

[0037] Fire-resistant reinforcement 5 is placed in the concrete 304 at the position of valley 3b. The fire-resistant reinforcement 5 extends in the span direction D1 at approximately the center of the internal space of valley 3b. The fire-resistant reinforcement 5 is placed at a height exceeding 40 mm of bottom cover. The bottom cover dimension is the height dimension from the bottom surface of valley 3b.

[0038] Crack expansion prevention reinforcement bars 8 are placed inside the concrete 304. The crack expansion prevention reinforcement bars 8 are placed above the crack expansion prevention reinforcement bars 7. The crack expansion prevention reinforcement bars 7 are placed at the position of the upper surface 100a of the concrete 4 before it is thickened.

[0039] A method for increasing the concrete thickness of a deck composite slab 300 will be described. This method is performed on an existing deck composite slab 200 shown in Figure 9(a). First, as shown in Figure 9(b), crack expansion prevention reinforcement 8 is placed directly on the existing concrete 4 of the deck composite slab 200. The crack expansion prevention reinforcement 8 is placed directly on the upper surface 100a of the existing concrete 4. The thickness of the concrete 304 is increased by pouring concrete 304a again. Here, additional concrete 304a is poured on the upper surface 100a of the existing concrete 4. This completes the deck composite slab 300.

[0040] Next, the performance of the deck composite slab 300 will be described with reference to Figs. 10 to 12. The test conditions are the same as those of the first embodiment, except that Example 2 shown in Fig. 10 is used as the test specimen for the deck composite slab 300. The test specimen for the comparative example is designated "No. 1," and the test specimen for Example 2 is designated "No. 2." Heating for "No. 1" for the comparative example was completed in 2 hours (120 minutes), and heating for "No. 2" for Example 1 was completed in 231 minutes.

[0041] Fig. 11 is a table showing the measurement results of the crest temperature detection sensor 102A and the valley temperature detection sensor 102B for evaluating the heat insulation performance. As shown in Fig. 11, compared to the comparative example "No. 1 crest 80 mm specification," the "No. 2 crest 115 mm specification" according to Example 2 has a thicker concrete thickness, so the temperature rise is more gradual, and it can be confirmed that the temperature remains below the specified value even after heating for more than three hours.

[0042] Fig. 12 is a table showing the measurement results of the deflection amount detection sensor 103 and used for evaluating non-damage. As shown in Fig. 12, the amount of deflection of "No. 2 115 mm upper peak specification" was slightly smaller than that of the comparative example "No. 1 80 mm upper peak specification" up to two hours of heating, but the rigidity remained stable even after three hours of heating, confirming that it had fire resistance for more than three hours.

[0043] The function and effect of the composite deck slab 300 according to this embodiment will be described.

[0044] The composite deck slab 300 according to this embodiment includes a deck plate 3 and concrete 304 poured on the deck plate 3. The concrete 304 has a thickness of more than 100 mm on the crest 3a of the deck plate 3. This allows the composite deck slab 300 to improve its fire resistance by providing a sufficiently thick concrete 304, thereby satisfying the fire resistance requirement of more than two hours in performance-based fire-resistant buildings. This allows for minor construction work, such as pouring additional concrete into an existing slab, to accommodate tenant changes to a use requiring a fire resistance period of more than two hours.

[0045] Fire-resistant reinforcement bars 5 may be placed in the concrete 304. In this case, the fire-resistant reinforcement bars 5 can suppress deformation of the deck composite slab 300.

[0046] The fire-resistant reinforcing bars 5 may be arranged at a height exceeding 40 mm of undercover. In this case, reinforcement by the fire-resistant reinforcing bars 5 can be performed at an appropriate height position.

[0047] The fire-resistant reinforcement 5 may be placed at a height of 45 mm or more below the concrete cover. 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 extended.

[0048] The fire-resistant reinforcement 5 may be arranged at a height of 45 mm to 65 mm below the cover. In this case, the fire-resistant time can be extended while efficiently bearing the bending that occurs at the tensile edge of the composite slab, further improving the fire resistance performance.

[0049] The thickness of the concrete 304 on the crest 3a of the deck plate 3 may be 115 mm or more. In this case, the fire resistance performance can be further improved.

[0050] In the case of the deck composite slab 1, if the required fire resistance time increases due to a change in the use of the room due to a tenant change or other reason, the concrete thickness can be increased by pouring the concrete again. In this case, the change in use of the room can be accommodated with minor construction work.

[0051] In the case of a composite deck slab 1, if the required fire resistance time exceeds two hours and a single pour would result in a concrete thickness that exceeds the safe range for construction, comparing the pouring load and the deck plate formwork performance, the concrete may be poured in two or more steps. In this case, the concrete thickness can be increased while ensuring safety for construction.

[0052] The concrete thickness increasing method for the composite deck slab 300 according to this embodiment involves placing crack expansion prevention bars 8 directly on the existing concrete 4 and pouring concrete 304a again to increase the thickness of the concrete 304. This achieves the same effects and aims as the composite deck slab 300 described above.

[0053] The present invention is not limited to the above-described embodiments.

[0054] For example, the shape of the deck plate may be modified as appropriate without departing from the spirit of the present invention. For example, a deck plate with a lower deck height than the deck plate shown in FIG. 2(a) may be adopted. Specifically, as with the deck plate 3 shown in FIG. 13(c), the deck plate shown in FIG. 2(a) may be used as the standard, and the height ratio to the standard shape may be 0.67. For example, a deck plate with a higher deck height than the deck plate shown in FIG. 2(a) may be adopted. Specifically, as with the deck plate 3 shown in FIG. 13(b), the height ratio to the standard shape may be 1.60. Furthermore, as with the deck plate 3 shown in FIG. 13(a), a deck plate with vertical ribs protruding upward from a substantially flat bottom surface may be adopted. Furthermore, the reinforcing bars placed inside the concrete may also be modified as appropriate. [Explanation of symbols]

[0055] 3...Deck plate, 4,304...Concrete, 5...Fire-resistant reinforcement, 6...Rock wool, 7,8...Crack prevention bars, 100,300...Deck composite slab.

Claims

1. A deck composite slab provided as a floor slab that requires a fire resistance performance of more than two hours in a fire-resistant design building with a performance-defined fire resistance performance verification, The composite deck slab is used in a fire-resistant building with advanced fire resistance performance verification (Route C), Deck plate and Concrete poured on the deck plate, The thickness of the concrete on the crest of the deck plate is greater than 100 mm, A fire-resistant reinforcement bar is disposed within the concrete; The fire-resistant reinforcement is arranged at a height of 45 mm or more and 65 mm or less below the cover. Deck composite slab.

2. 2. The composite deck slab according to claim 1, wherein the thickness of the concrete on the crest of the deck plate is 115 mm or more.

3. A composite deck slab as described in claim 1 or claim 2, in which the required fire resistance time has increased due to a change in the use of the room due to a tenant change or the like, and the concrete thickness has been increased by pouring concrete again.

4. The composite deck slab according to any one of claims 1 to 3, wherein the required fire resistance time is more than two hours, and a single pouring step results in a concrete thickness that exceeds the safe range for construction when comparing the pouring load and the formwork performance of the deck plate, and the concrete is poured in two or more steps.

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