Composite deck slab, and method for improving the fire resistance of composite deck slab.

Abstract

This invention provides a deck composite slab that can be used as a floor slab requiring fire resistance exceeding 2 hours in performance-based fire-resistant buildings, and a method for improving the fire resistance of the deck composite slab. [Solution] The deck composite slab 100 comprises a deck plate 3, concrete 4 poured on the deck plate 3, and rock wool 6 covering the deck plate 3. As a result, the deck composite slab 100 can protect the heated surface (bottom surface 3c) of the deck plate 3 with the rock wool 6, thereby improving fire resistance and meeting the requirement of fire resistance exceeding 2 hours in performance-based fire-resistant buildings. This makes it possible to use it in fire-resistant design for advanced fire resistance performance verification (Route C), enabling more economical designs than before.

Description

Technical Field

[0001] The present invention relates to a deck composite slab and a method for improving the fire resistance performance of a deck composite slab.

Background Art

[0002] As a conventional deck composite slab, the one described in Patent Document 1 is known. This deck composite slab includes a deck plate and concrete placed on the deck plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, among the fire resistance design routes defined by the Building Standards Law, generally Route A of the specification type is adopted for the deck composite slab (see Fig. 3). On the other hand, although Route C of the performance type requires advanced design know-how, it is possible to perform an optimal design because the required performance and retention performance in terms of fire resistance are evaluated for each room unit, and the cost reduction effect is high in large-scale properties.

[0005] The required performance of deck composite slabs differs depending on the design route (see, for example, Figure 4). Specifically, in the fire-resistant design of Route A, the required fire resistance time for the floor is determined according to the number of floors, but the required fire resistance time is a maximum of 2 hours. In addition, the heat shielding performance is 1.2 hours (72 minutes) by multiplying 1 hour by a safety factor of 1.2. On the other hand, in the fire-resistant design of Route C, the required performance is determined by the amount of heat generated and the amount of heat intrusion, so there are cases where fire resistance performance (including heat shielding) of more than 2 hours is required. To meet such requirements, a configuration in which fire-resistant reinforcing bars are installed in the concrete of the deck composite slab is sometimes adopted. However, although these fire-resistant reinforcing bars have the effect of suppressing deformation, they do not have the effect of improving heat shielding, so there has been a problem in that it is difficult to ensure fire resistance performance of more than 2 hours with conventional deck composite slabs.

[0006] Furthermore, in buildings designed using Route C, if there is a change in the use of a room, such as a change in tenants, the preconditions change from those at the time of design. As a result, the required fire resistance time increases, and areas that were initially eligible for 2 hours of fire resistance may now require more than 2 hours of fire resistance.

[0007] This invention was made to solve these problems, and aims to provide a deck composite slab that can be used as a floor slab required to have fire resistance performance exceeding 2 hours in a performance-based fire-resistant building, and a method for improving the fire resistance performance of the deck composite slab. [Means for solving the problem]

[0008] The deck composite slab according to the present invention is a deck composite slab provided as a floor slab required to have fire resistance performance exceeding 2 hours in a fire-resistant building designed for performance-based fire resistance performance verification, and comprises a deck plate, concrete cast on the deck plate, and rock wool covering the deck plate, and the deck composite slab is used in a fire-resistant building designed for advanced fire resistance performance verification (Route C), and fire-resistant reinforcing bars are placed in the concrete, and the fire-resistant reinforcing bars are placed at a height of 45 mm to 65 mm below the concrete cover.

[0009] The rock wool may be formed by spraying granular rock wool onto the underside of the deck plate, and the thickness of the rock wool coating may be 25 mm or more and 35 mm or less.

[0010] The rock wool may have a shape that corresponds to the underside of the deck plate.

[0011] The present invention relates to a method for improving the fire resistance of a deck composite slab, which is provided as a floor slab required to have fire resistance exceeding 2 hours in a fire-resistant building designed for performance-based fire resistance verification. The method involves spraying rock wool onto the deck composite slab, which comprises a deck plate and concrete poured on the deck plate. The lower surface of the deck plate is covered with sprayed rock wool. The deck composite slab is used in fire-resistant buildings designed for advanced fire resistance verification (Route C), and fire-resistant reinforcing bars are placed within the concrete, with the fire-resistant reinforcing bars positioned at a height of 45 mm to 65 mm below the concrete cover. [Effects of the Invention]

[0012] According to the present invention, a deck composite slab that can be provided as a floor slab required to have fire resistance performance exceeding 2 hours in a performance-based fire-resistant building, and a method for improving the fire resistance performance of the deck composite slab can be provided. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view of a deck composite slab according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view along line II-II in Figure 1. [Figure 3] This diagram shows the fire-resistant design route. [Figure 4] This table shows the main differences between Route A and Route C in deck composite slabs. [Figure 5] This is a diagram showing the test method. [Figure 6] This is a table showing the test conditions. [Figure 7] It is a table showing the measurement results of the temperature detection sensors on the ridges and the valleys, and for conducting a heat insulation performance evaluation. [Figure 8] It is a table showing the measurement results of the deflection amount detection sensor, and for conducting a non-destructive evaluation. [Figure 9] It is a cross-sectional view for explaining the deck composite slab according to the second embodiment of the present invention, and a concrete thickening method for manufacturing the deck composite slab. [Figure 10] It is a table showing the test conditions. [Figure 11] It is a table showing the measurement results of the temperature detection sensors on the ridges and the valleys, and for conducting a heat insulation performance evaluation. [Figure 12] It is a table showing the measurement results of the deflection amount detection sensor, and for conducting a non-destructive evaluation. [Figure 13] It is a cross-sectional view showing a deck plate according to a modified example.

Embodiments for Carrying out 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 the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. The deck composite slab 100 is provided as a floor slab that requires a fire resistance performance exceeding 2 hours in a performance-specified (in advanced fire resistance performance verification) fire-resistant design building.

[0016] Here, the fire resistance design route will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing the fire resistance design route. FIG. 3 is a diagram defined in the "Guidebook on the Fire Resistance of Structural Materials (Architectural Institute of Japan)". For the deck composite slab 100, generally, Route A of the prescriptive type is adopted among the fire resistance design routes defined by the Building Standards Law. On the other hand, although Route C of the performance-based type requires advanced design know-how, optimal design is possible because the required fire resistance performance and the possessed performance are evaluated for each room unit, and the cost reduction effect is high for large-scale properties. The main differences between Route A and Route C in the deck composite slab 100 are shown in the table of FIG. 4.

[0017] Regarding the fire resistance performance, in the fire resistance performance confirmation test shown in FIG. 5, based on the "Method Book for Fire Resistance Performance Test and Evaluation Business", the heat insulation performance and non-damage performance are evaluated. The heat insulation performance is evaluated by the temperature rise on the back surface (upper surface) of the deck composite slab 100. The non-damage performance is evaluated by the deflection amount BA of the deck composite slab 100. As shown in FIG. 5(a), the test specimen of the deck composite slab 100 is placed on the fire furnace 101, a constant load is applied to the upper surface, and the temperature rise and the deflection amount BA are measured. The more detailed content of the test will be described later.

[0018] As shown in FIG. 4, there are differences in the required performance depending on the design route. Specifically, in the fire resistance design of Route A, the required fire resistance time of the floor is determined according to the number of floors, but the required fire resistance time is at most 2 hours. Also, in terms of heat insulation performance, it is 1.2 hours (72 minutes) with a safety factor of 1.2 applied to 1 hour. On the other hand, in the fire resistance design of Route C, since the required performance is determined from the heat generation amount, the intrusion heat amount, etc., there are cases where fire resistance performance (including heat insulation performance) exceeding 2 hours is required.

[0019] Here, as a comparative example, there is the deck composite slab 200 provided with the fire resistance reinforcing bars 5 as shown in FIG. 2(b). Although this fire resistance reinforcing bar 5 has the effect of suppressing deformation, it has no effect on improving the heat insulation performance. Therefore, it is difficult to ensure fire resistance performance exceeding 2 hours with the deck composite slab 200 according to the comparative example.

[0020] As described above, in fire-resistant design using Route C, there are cases where fire resistance performance exceeding 2 hours is required, and the fire-resistant reinforcement bars in the deck composite slab 200 in the comparative example are insufficient to improve heat shielding performance. Furthermore, increasing the concrete thickness increases the weight of the slab, which may affect other members, such as requiring larger columns and beams, and an increase in the number of secondary beams.

[0021] In contrast, the deck composite slab 100 according to this embodiment is provided as a floor slab required to have fire resistance performance exceeding 2 hours in a fire-resistant building with advanced fire resistance performance verification (Route C). Specifically, the deck composite slab 100 comprises a deck plate 3, concrete 4, and rock wool 6. The deck composite slab 100 is supported by a pair of beam members 2.

[0022] As shown in Figure 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 surface of the valleys 3b. Multiple peaks 3a are spaced apart from each other in the width direction D2 and extend parallel to each other in the span direction D1. The peaks 3a form the 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 upper surface of the peaks 3a. As a result, the concrete 4 has an upper surface that extends in the span direction D1 and the width direction D2 above the deck plate 3. 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 propagation prevention reinforcement bars 7 are placed inside the concrete 4. The crack propagation prevention reinforcement bars 7 are mesh members that extend parallel to the span direction D1 and the width direction D2. The crack propagation prevention reinforcement bars 7 are placed between the peak portion 3a and the upper surface 100a.

[0025] Rock wool 6 is a component that covers the deck plate 3. Rock wool 6 is formed by spraying granular rock wool onto the lower surface 3c of the deck plate 3. 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 covering thickness of rock wool 6 may be greater than 20 mm and 25 mm or more. Also, the covering thickness of rock wool 6 may be 65 mm or less. However, since it is sprayed onto the lower surface, it is desirable to carry out the covering with a thickness of 25 mm or more and 35 mm or less from the viewpoint of preventing detachment.

[0026] Next, the performance of the deck composite slab 100 will be described with reference to Figures 5 to 8. Figure 5 is a diagram showing the test method. Figure 6 is a table showing the test conditions for Example 1 and the comparative example. First, as shown in Figure 5(b), the dimension L1 of the support span in the span direction D1 of the deck composite slab 100 relating to the test specimen is 3600 mm, and the dimension W1 in the width direction D2 is 2000 mm. In the deck plate of the deck composite slab 100, the pitch between peaks in the width direction D2 is 300 mm. Also, valleys are arranged at the ends of the deck plate of the deck composite 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 deck composite slab 100 and the end of the deck plate 3 is 250 mm. As shown in Figure 5(b), temperature detection sensors 102A, 102B and deflection detection sensor 103 are provided on the upper surface 100a of the deck composite slab 100. The dimension L2 from one support point in the span direction D1 of the temperature detection sensors 102A and 102B is 900 mm. Temperature detection sensor 102A is located at the center of the first peak from end 100b, and the dimension W2 in the width direction D2 from end 100b is 250 mm. Temperature detection sensor 102B is located at the center of the second valley from end 100c, and the dimension W3 in the width direction D2 from end 100c is 400 mm. 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 end 100b is 1000 mm. Other conditions are shown in Figure 6. Note that the test specimen related to the comparative example is designated as "No. 1", and the test specimen related to Example 1 is designated as "No. 2". For Comparative Example No. 1, heating was completed after 2 hours (120 minutes), and for Example 1 No. 2, heating was completed after 3 hours (180 minutes).

[0027] Figure 7 shows the measurement results of the temperature detection sensor 102A in the peak section and the temperature detection sensor 102B in the valley section, and is a table for evaluating the heat shielding performance. As shown in Figure 7, regarding the temperature of the upper surface 100a, compared with the comparative example "No. 1 fire-resistant reinforcement specification" in which the deck plate is exposed to the heated surface (bottom surface), the temperature rise is more gradual in the "No. 2 rock wool coated specification" according to Example 1, and it can be confirmed that it remains below the specified value even after 3 hours (180 minutes) of heating.

[0028] Figure 8 shows the measurement results of the deflection detection sensor 103 and is a table for evaluating non-damage. As shown in Figure 8, regarding the amount of deflection, compared with the "No. 1 fire-resistant reinforcement specification" in the comparative example, the "No. 2 rock wool coated specification" in Example 1 shows a more gradual increase in deflection, and it can be confirmed that it remains below the specified value even after 3 hours of heating. The "No. 2 rock wool coated specification" in Example 1 is coated with rock wool, which delays the decrease in strength due to the temperature rise of the deck plate and the decrease in the Young's modulus of the concrete.

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

[0030] The deck composite slab 100 according to this embodiment comprises a deck plate 3, concrete 4 poured on the deck plate 3, and rock wool 6 covering the deck plate 3. As a result, the deck composite slab 100 can protect the heated surface (bottom surface 3c) of the deck plate 3 with the rock wool 6, thereby improving fire resistance and meeting the requirement of fire resistance exceeding 2 hours in performance-based fire-resistant buildings. This makes it possible to use it in fire-resistant design for advanced fire resistance performance verification (Route C), enabling more economical designs than before.

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

[0032] The thickness of the rock wool 6 coating may be 25 mm or more and 35 mm or less. In this case, the fire resistance 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 lower surface 3c 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 covering thickness of the rock wool 6 can be set to an appropriate thickness to match the shape of the lower surface 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 provided as a floor slab required to have fire resistance exceeding 2 hours in a fire-resistant design building in a performance-based fire resistance performance verification, by spraying rock wool, and involves applying a sprayed rock wool coating to the lower surface 3c of the deck plate 3 of the deck composite slab 100, which comprises a deck plate 3 and concrete 4 poured on the deck plate 3.

[0035] According to the method for improving the fire resistance of the deck composite slab 100 as described above, the same effects and benefits as those of the deck composite slab 100 can be obtained.

[0036] [Second Embodiment] Figure 9 is a cross-sectional view illustrating 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. The deck composite slab 300 shown in Figure 9(c) is provided as a floor slab required to have fire resistance performance exceeding 2 hours in a performance-based fire-resistant building. The deck composite slab 300 comprises concrete 304 that is thicker than the concrete 4 of the deck composite slab 100 shown in Figure 2. The thickness t2 of the concrete 304 on the ridge portion 3a of the deck plate 3 is greater than 100 mm and may be 115 mm or more. The thickness t2 of the concrete 304 may be 150 mm or less.

[0037] Within the concrete 304, fire-resistant reinforcing bars 5 are placed at the location of the valley section 3b. The fire-resistant reinforcing bars 5 extend in the span direction D1 at approximately the center of the internal space of the valley section 3b. The fire-resistant reinforcing bars 5 are placed at a height exceeding 40 mm of concrete cover. The concrete cover dimension is the height dimension from the bottom surface of the valley section 3b.

[0038] Crack expansion prevention reinforcement bars 8 are placed inside the concrete 304. The crack expansion prevention reinforcement bars 8 are positioned above the crack expansion prevention reinforcement bars 7. The crack expansion prevention reinforcement bars 7 are positioned at the top surface 100a of the concrete 4 before thickening.

[0039] This section describes a method for increasing the concrete thickness of a deck composite slab 300. This method is applied to an existing deck composite slab 200 shown in Figure 9(a). First, as shown in Figure 9(b), crack expansion prevention reinforcement bars 8 are directly placed on the existing concrete 4 of the deck composite slab 200. The crack expansion prevention reinforcement bars 8 are 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, the 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 Figures 10 to 12. The test conditions are the same as in the first embodiment, except that Example 2 shown in Figure 10 is used as the test specimen for the deck composite slab 300. The test specimen for the comparative example is designated as "No. 1," and the test specimen for Example 2 is designated as "No. 2." Heating for "No. 1" (comparative example) was completed after 2 hours (120 minutes), and heating for "No. 2" (Example 1) was completed after 231 minutes.

[0041] Figure 11 shows the measurement results of the temperature detection sensor 102A in the peak section and the temperature detection sensor 102B in the valley section, and is a table for evaluating the heat shielding performance. As shown in Figure 11, compared to the comparative example "No. 1 peak 80mm specification", the "No. 2 peak 115mm specification" in Example 2 has a thicker concrete, resulting in a slower temperature rise, and it can be confirmed that the temperature remains below the specified value even after more than 3 hours of heating.

[0042] Figure 12 shows the measurement results of the deflection detection sensor 103 and is a table for evaluating non-damage. As shown in Figure 12, the deflection of the "No. 2 mountain top 115 mm specification" was only slightly smaller than that of the comparative example "No. 1 mountain top 80 mm specification" up to 2 hours of heating. However, the rigidity remained stable even after exceeding 3 hours of heating, confirming that it has fire resistance performance for more than 3 hours.

[0043] The operation and effects of the deck composite slab 300 according to this embodiment will be explained.

[0044] The deck composite slab 300 according to this embodiment comprises a deck plate 3 and concrete 304 poured on the deck plate 3. Of these, the thickness of the concrete 304 on the ridge portion 3a of the deck plate 3 is greater than 100 mm. As a result, the deck composite slab 300 improves fire resistance by making the thickness of the concrete 304 sufficiently thick, and can meet the requirement of fire resistance exceeding 2 hours in performance-based fire-resistant buildings. This makes it possible to accommodate changes in tenant use to applications requiring fire resistance exceeding 2 hours with minor construction, for example, by adding concrete to the existing slab.

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

[0046] The fire-resistant reinforcing bars 5 may be placed at a height exceeding 40 mm of concrete cover. In this case, reinforcement with fire-resistant reinforcing bars 5 can be performed at an appropriate height.

[0047] The fire-resistant reinforcement bars 5 may be placed at a height of 45 mm or more below the concrete cover. In this case, increasing the concrete cover thickness can delay the temperature rise of the fire-resistant reinforcement bars, thereby extending the fire resistance time.

[0048] The fire-resistant reinforcement bars 5 may be placed at a height of 45 mm to 65 mm below the concrete cover. In this case, the fire resistance 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 ridge portion 3a of the deck plate 3 may be 115 mm or more. In this case, the fire resistance can be further improved.

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

[0051] In the deck composite slab 1, the required fire resistance time exceeds 2 hours, and the specification is such that a single concrete pour results in a concrete thickness exceeding the safe range for construction when comparing the pouring load and the formwork performance of the deck plate. Therefore, the concrete may be poured in two or more stages. In this case, the concrete thickness can be increased while ensuring construction safety.

[0052] The concrete thickening method for the deck composite slab 300 according to this embodiment involves directly placing crack-expansion prevention reinforcement bars 8 on the existing concrete 4 and then pouring concrete 304a again to increase the thickness of the concrete 304. This makes it possible to obtain the same effects and functions as the deck composite slab 300 described above.

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

[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 Figure 2(a) may be adopted. Specifically, as shown in Figure 13(c), the deck plate shown in Figure 2(a) may be used as the standard type, and the height ratio to the standard type may be set to 0.67. For example, a deck plate with a higher deck height than the deck plate shown in Figure 2(a) may be adopted. Specifically, as shown in Figure 13(b), the height ratio to the standard type may be set to 1.60. Also, as shown in Figure 13(a), a deck plate of the vertical rib type may be adopted, in which ribs protrude upward from a bottom surface that is formed in a substantially flat shape. Furthermore, the reinforcing bars arranged inside the concrete may also be modified as appropriate. [Explanation of symbols]

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

Claims

1. In a fire-resistant building designed for performance-based fire resistance verification, a deck composite slab is provided as a floor slab requiring fire resistance exceeding two hours, Deck plate and Concrete poured onto the deck plate, The deck plate is covered with rock wool, The aforementioned deck composite slab is used in fire-resistant buildings under advanced fire resistance performance verification (Route C), Fire-resistant reinforcing bars are placed within the aforementioned concrete. The aforementioned fire-resistant reinforcing bars are positioned at a height of 45 mm to 65 mm below the ground cover. Deck composite slab.

2. The deck composite slab according to claim 1, wherein the rock wool is formed by spraying granular rock wool cotton onto the lower surface of the deck plate, and the thickness of the rock wool coating is 25 mm or more and 35 mm or less.

3. The deck composite slab according to claim 1 or 2, wherein the rock wool has a shape corresponding to the lower surface of the deck plate.

4. The deck composite slab according to claim 1 or 2, wherein the deck composite slab has fire resistance performance that is below the specified values ​​for heat shielding and non-damage after heating for 3 hours (180 minutes).

5. A method for improving the fire resistance of a deck composite slab, provided as a floor slab required to have fire resistance exceeding 2 hours in a fire-resistant building designed for performance-based fire resistance verification, by spraying rock wool, A deck composite slab comprising a deck plate and concrete poured on the deck plate is coated with sprayed rock wool on the underside of the deck plate. The aforementioned deck composite slab is used in fire-resistant buildings under advanced fire resistance performance verification (Route C), Fire-resistant reinforcing bars are placed within the aforementioned concrete. The aforementioned fire-resistant reinforcing bars are positioned at a height of 45 mm to 65 mm below the ground cover. Methods for improving the fire resistance of composite deck slabs.

Images