Fire-resistant structure, and construction method of fire-resistant structure

Abstract

This invention provides a fire-resistant structure and a construction method thereof that can enhance the fire resistance performance of floor slabs. [Solution] The fire-resistant structure comprises a cement composition layer 12, a fire-resistant coating layer 13 provided below the cement composition layer 12, and a locking mechanism 30 embedded in the cement composition layer 12 and the fire-resistant coating layer 13 to lock the fire-resistant coating layer 13 to the cement composition layer 12. The locking mechanism 30 comprises a mesh material 31 as a locking material and a locking material support 32 that engages with the cement composition layer 12 to support the mesh material 31. The embedded material 33 constituting the locking material support 32 is installed before or after the cement composition is poured and engages with the cement composition layer 12.

Description

Technical Field

[0001] The present invention relates to a fire-resistant structure and a method for constructing a fire-resistant structure.

Background Art

[0002] Conventionally, as a fire-resistant structure of a composite slab having a structural steel plate and a cement composition layer provided on the steel plate, a fire-resistant structure such as that of Patent Document 1 is known. In Patent Document 1, with respect to a composite slab in which a cement composition is placed using a structural steel plate having peaks and valleys as a bottom formwork, a heat-insulating space is formed between the valley of the steel plate and a fire-resistant coating material so that the fire-resistant coating material is disposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Reinforced concrete slabs are structurally designed to ensure safety against constant loads and seismic loads, but in addition, fire safety during a fire must also be ensured. Measures to maintain the specified load-bearing capacity during a fire include increasing the concrete cover thickness, increasing the amount of reinforcing steel, or increasing the diameter of the reinforcing steel to suppress the temperature rise of the reinforcing steel (bottom main reinforcement). Furthermore, from the perspective of ensuring fire spread prevention to upper and lower floors, measures to improve insulation performance by increasing the slab thickness can be considered. However, increasing the concrete cover thickness and slab thickness, or increasing the amount of reinforcing steel, increases the weight of the slab itself, which in turn increases the constant loads and seismic loads, leading to problems that adversely affect structural performance. Moreover, once a reinforced concrete slab has been constructed, it is impossible to increase the concrete cover thickness or the amount of reinforcing steel, making it difficult to improve fire resistance after the slab has been constructed. One possible fire-resistant measure to avoid these problems is to apply a fire-resistant coating, which is lighter than reinforcing steel or concrete, to the underside of the slab. However, since the underside of a reinforced concrete slab is a smooth surface without irregularities, there is a very high risk that the fire-resistant coating will fall off. The present invention aims to solve the above problems by providing a method to improve fire resistance while minimizing the increase in the self-weight of the slab, and furthermore, a method that can improve fire resistance even after the construction of the reinforced concrete slab. [Means for solving the problem]

[0005] A fire-resistant structure that solves the above problems comprises a cement composition layer, a fire-resistant coating layer provided below the cement composition layer, and a locking mechanism having an engaging portion that engages with the cement composition layer and locks the fire-resistant coating layer to the cement composition layer.

[0006] A method for constructing a fire-resistant structure that solves the above problems is a method for constructing a fire-resistant structure having a cement composition layer and a fire-resistant coating layer provided below the cement composition layer, comprising: a mounting hole forming step of forming mounting holes in a bottom formwork; a buried material mounting step of attaching buried material to the mounting holes; a pouring step of pouring a cement composition into the bottom formwork so that the buried material is buried; a locking material mounting step of attaching a locking material to lock the fire-resistant coating layer to the buried material buried in the cement composition layer; and a fire-resistant coating layer forming step of spraying a spray fire-resistant coating material toward the cement composition layer so that the locking material is buried.

[0007] A method for constructing a fire-resistant structure that solves the above problems is a method for constructing a fire-resistant structure having a cement composition layer and a fire-resistant coating layer provided below the cement composition layer, comprising: a casting step of casting the cement composition into a bottom formwork; a mounting hole forming step of forming mounting holes in the cement composition layer; a mounting material installation step of inserting a drive-in type embedding material into the mounting holes and driving the embedding material into the cement composition layer; a locking material installation step of attaching a locking material to lock the fire-resistant coating layer to the embedding material driven into the cement composition layer; and a fire-resistant coating layer forming step of spraying a spray-on fire-resistant coating material toward the cement composition layer so that the locking material is embedded.

[0008] According to the above configuration, the fire-resistant coating layer is secured to the cement composition layer, preventing it from falling off during a fire. This enhances fire resistance. Furthermore, the securement of the fire-resistant coating layer to the cement composition layer increases the flexibility of the fire-resistant coating layer's thickness. This means that even if it becomes necessary to improve the fire resistance of the floor slab after the initial design, this can be addressed by increasing the thickness of the fire-resistant coating layer.

[0009] The fire-resistant structure with the above configuration does not necessarily have a structural steel plate between the cement composition layer and the fire-resistant coating layer. In the construction method of the fire-resistant structure with the above configuration, the bottom formwork may be a wooden formwork and may be removed after the pouring process. This allows, for example, the cement composition layer and the fire-resistant coating layer to be in direct contact.

[0010] The fire-resistant structure with the above configuration may have a steel sacrificial formwork between the cement composition layer and the fire-resistant coating layer. In the construction method of the fire-resistant structure with the above configuration, the bottom formwork may be a steel sacrificial formwork and may be buried. This allows for a configuration in which a steel sacrificial formwork is placed between the cement composition layer and the fire-resistant coating layer.

[0011] In the above configuration, the fire-resistant coating layer is preferably a spray-applied fire-resistant coating material. This allows the thickness of the fire-resistant coating layer to be adjusted by the amount of spray-applied fire-resistant coating material applied. In the above configuration, it is preferable that the locking mechanism includes an embedded material embedded in the cement composition layer as a member having the engaging portion. This allows the cement composition layer and the locking material to be engaged by pouring the cement composition. In other words, it is not necessary to form mounting holes in the cement composition layer for attaching the locking mechanism. As a result, the burden on workers associated with installing the locking mechanism can be reduced.

[0012] In the above configuration, it is preferable that the locking mechanism has a locking member that is joined to the buried material and locks the fire-resistant coating layer. As a result, the fire-resistant coating layer becomes entangled with the locking member, thereby increasing the locking force of the fire-resistant coating layer by the locking mechanism. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic cross-sectional view showing the general configuration of the fire-resistant structure in the first embodiment. [Figure 2] A schematic diagram showing the basic structure of the locking mechanism in the first embodiment. [Figure 3]In the first embodiment, a diagram showing an example of the construction procedure in the first example of the construction method of the fire-resistant structure. [Figure 4] (a) A diagram schematically showing the state of attaching an insert to the bottom formwork, (b) A diagram schematically showing the state where the insert is temporarily fixed to the bottom formwork. [Figure 5] (a) A diagram schematically showing the state of attaching a mesh material to the insert, (b) A diagram schematically showing the state where the mesh material is attached to the insert. [Figure 6] In the first embodiment, a diagram showing an example of the construction procedure in the second example of the construction method of the fire-resistant structure. [Figure 7] (a) A diagram schematically showing the state of inserting an anchor into the cement composition layer, (b) A diagram schematically showing the state where the driving of the anchor into the cement composition layer is completed. [Figure 8] A cross-sectional view schematically showing the schematic configuration of the fire-resistant structure in the second embodiment. [Figure 9] A perspective view showing an example of the truss bars. [Figure 10] A diagram schematically showing the basic structure of the locking mechanism in the second embodiment. [Figure 11] In the second embodiment, a diagram showing an example of the construction procedure in the first example of the construction method of the fire-resistant structure. [Figure 12] (a) A diagram schematically showing the state where an insert is temporarily fixed to the steel disposable formwork, (b) A diagram schematically showing the state where a mesh material is attached to the insert. [Figure 13] In the second embodiment, a diagram showing an example of the construction procedure in the second example of the construction method of the fire-resistant structure. [Figure 14] (a) A diagram schematically showing the state of inserting an anchor into the cement composition layer, (b) A diagram schematically showing the state where the driving of the anchor into the cement composition layer is completed.

Modes for Carrying Out the Invention

[0014] (First Embodiment) Referring to FIGS. 1 to 7, a first embodiment of a fireproof structure and a construction method of the fireproof structure will be described.

[0015] As shown in FIG. 1, the fireproof structure 10 is applied to a floor slab that requires fireproof performance. The fireproof structure 10 has a cement composition layer 12, a fireproof coating layer 13, and a locking mechanism 30.

[0016] The cement composition layer 12 is formed by curing a cement composition cast against a bottom formwork (wooden formwork) that will be disassembled later, such as a plywood. Various reinforcing bars are embedded in the cement composition layer 12. In this embodiment, an upper main reinforcing bar 21 and a lower main reinforcing bar 22 are embedded.

[0017] The cement composition is a fluid obtained by kneading at least cement and water. The cement composition is, for example, concrete obtained by kneading a cement mixture obtained by mixing gravel or sand, which is an aggregate, with cement and water. The cement composition may be a mortar such as Slimcrete (registered trademark), or may be a mixture containing fibers (fiber-reinforced concrete material).

[0018] The upper main reinforcing bar 21 and the lower main reinforcing bar 22 extend along a first direction in the plane direction of the cement composition layer 12. The upper main reinforcing bar 21 is disposed above the lower main reinforcing bar 22. The upper main reinforcing bar 21 and the lower main reinforcing bar 22 are arranged side by side in a second direction orthogonal to the first direction in the plane direction of the cement composition layer 12.

[0019] The fireproof coating layer 13 is provided under the cement composition layer 12. The fireproof coating layer 13 covers the lower surface 12a of the cement composition layer 12. The fireproof coating layer 13 is formed by curing a sprayed fireproof coating material sprayed from below onto the cement composition layer 12 using a spraying machine. An example of the sprayed fireproof coating material is sprayed rock wool. Sprayed rock wool is a fluid containing cement as a curing material with granular rock wool fibers as the main raw material.

[0020] The locking mechanism 30 is a mechanism for locking the fire-resistant coating layer 13 to the cement composition layer 12. The locking mechanism 30 is embedded in the cement composition layer 12 and the fire-resistant coating layer 13 so as to straddle both layers.

[0021] (Basic structure of the locking mechanism) As shown in Figure 2, the locking mechanism 30 includes a mesh material 31 as a locking material for locking the fire-resistant coating layer 13 and a locking material support 32 for supporting the locking material.

[0022] The mesh material 31 is preferably composed of one or more metal meshes with a relatively coarse mesh size, such as wire mesh (e.g., 50-100 mm x 50-100 mm x φ1.6-6.0). The mesh material 31, which is the locking material, is arranged to cover the entire lower surface 12a of the cement composition layer 12.

[0023] The locking support members 32 are fixed to the cement composition layer 12. The locking support members 32 are arranged in a grid pattern at predetermined intervals, for example, between 300 mm and 1200 mm. Each locking support member 32 consists of an embedded material 33, a spacer 34, a retaining material 35, and a stopper 36.

[0024] The embedded material 33 is a component embedded in the cement composition layer 12. The embedded material 33 has an engaging portion 33a near its upper end, which has a larger diameter than other parts and engages with the cement composition layer 12. The embedded material 33 has a female threaded portion (not shown) at its lower end.

[0025] The spacer 34 is placed between the cement composition layer 12 and the mesh material 31. The spacer 34 is a flat plate-shaped member with a mesh size larger than that of the mesh material 31. The spacer 34 maintains the distance between the cement composition layer 12 and the mesh material 31. The spacer 34 is preferably an annular member.

[0026] The retaining member 35 is a member disposed between the mesh material 31 and the head of the stopper 36, and is a flat plate-shaped member with a larger mesh size than the mesh material 31. Preferably, the retaining member 35 is an annular member.

[0027] The stopper 36 is a bolt fastened to the embedded material 33. The shaft of the stopper 36 is screw-connected to the lower end of the embedded material 33 through each of the members 31, 34, and 35. The head of the stopper 36 has a shape that prevents the retaining member 35 from falling out. By fastening the stopper 36 to the embedded material 33, the stopper 36 presses each of the members 31, 34, and 35 against the cement composition layer 12.

[0028] (First example of construction method in the first embodiment) Referring to Figures 3 to 5, a first example of a construction method for the fire-resistant structure 10 will be described. This first example of a construction method is applicable when improvement of fire resistance is required before the cement composition is poured.

[0029] As shown in Figure 3, in the first example of the construction method for the fire-resistant structure 50, the following steps are performed in order: formwork installation (step S101), mounting hole formation (step S102), embedded material installation (step S103), concrete pouring (step S104), formwork removal (step S105), locking material installation (step S106), and fire-resistant coating layer formation (step S107).

[0030] As shown in Figure 4(a), in the formwork installation process (step S101), for example, plywood is installed as the bottom formwork 38. The bottom formwork 38 is, for example, connected at its periphery to the beam 16 (H-shaped steel, etc.) and supported on the inside of its periphery by a bottom formwork support located on the lower floor. In addition, the upper main reinforcement bars 21 and lower main reinforcement bars 22 are installed above the bottom formwork 38.

[0031] In the mounting hole formation process (step S102), mounting holes 39 are formed in the bottom formwork 38 at the mounting positions for the embedded material 33 using a drill or the like. In the embedded material installation process (step S103), the insert 40, which is the embedded material 33, is attached to the bottom formwork 38.

[0032] In the buried material installation process (step S103), the buried material 33 is attached to the bottom formwork 38. The embedded material 33 used in the first example of the construction method for fire-resistant structures is an insert 40. The insert 40 is a member embedded in the cement composition layer 12 by pouring the cement composition. An example of the insert 40 has a spring 41, a support plate 42, and a temporary fixing bolt 43. The spring 41 is arranged to surround the insert 40. The insert 40 has a flange portion 40a at its upper end that functions as an engaging portion 33a. The spring 41 is a compression spring supported by the flange portion 40a at the upper end of the insert 40 and by the support plate 42 at the lower end of the insert 40. The support plate 42 is a flat, annular member through which the insert 40 passes. The temporary fixing bolt 43 is a temporary fixing member connected to the lower end of the insert 40. The temporary fixing bolt 43 has a temporary fixing portion 44. The temporary fixing portion 44 restricts the displacement of the support plate 42 before the insert 40 is attached to the bottom formwork 38. Furthermore, the temporary fastening portion 44 snaps into place on the bottom formwork 38 by inserting the temporary fastening bolt 43 into the mounting hole 39.

[0033] As shown in Figure 4(b), the insert 40 is attached to the bottom formwork 38 by inserting temporary fastening bolts 43 into mounting holes 39 from the cement composition layer 12 forming side, and the temporary fastening portion 44 snap-fitting to the bottom formwork 38. At this time, the insert 40 is held between the support plate 42 and the temporary fastening portion 44 by the biasing force of the spring 41, and is displaceable through the mounting holes 39 in the extending direction of the insert 40, returning to the state shown in Figure 4(b). With this configuration, even if a downward load is applied to the insert 40 during cement composition pouring, the load can be absorbed by the spring 41. As a result, the insert 40 is less likely to come off.

[0034] In the pouring process (step S104), the side formwork is installed in the designated position, and then the cement composition is poured onto the bottom formwork 38. The formwork removal process (step S105) is performed after the cement composition has cured. In the formwork removal process, the formwork, such as the bottom formwork 38, is removed.

[0035] As shown in Figure 5(a), in the locking material installation process (step S106), after removing the temporary fastening bolts 43 from the insert 40, spacers 34 are placed at various locations so as to abut against the lower surface 12a of the cement composition layer 12. Then, with the mesh material 31 and the retaining material 35 in place, the stopper 36 is fastened to the insert 40. As a result, the mesh material 31 is attached to the insert 40, as shown in Figure 5(b).

[0036] In the fire-resistant coating layer formation process (step S107), a spray coating material is sprayed onto the entire lower surface 12a of the cement composition layer 12, starting from the lower floor. Then, the fire-resistant coating layer 13 is formed as the spray coating material dries and hardens.

[0037] (Second example of the construction method in the first embodiment) Referring to Figures 6 and 7, a second example of the construction method for the fire-resistant structure 10 will be described. This second example of the construction method can be used even when improvement of fire resistance performance becomes necessary after the cement composition has been poured.

[0038] As shown in Figure 6, in the second example of the construction method for the fire-resistant structure 50, the following steps are performed in order: formwork installation (step S201), concrete pouring (step S202), formwork removal (step S203), mounting hole formation (step S204), embedded material installation (step S205), locking material installation (step S206), and fire-resistant coating layer formation (step S207).

[0039] The formwork installation process (step S201), concrete pouring process (step S202), formwork removal process (step S203), and fire-resistant coating layer formation process (step S207) are the same as those in the first example of the construction method in the first embodiment. Therefore, only the mounting hole formation process (step S204), embedded material installation process (step S205), and locking material installation process (step S206) will be described here.

[0040] As shown in Figure 7(a), in the mounting hole formation step (step S204), mounting holes 45 of a predetermined depth are formed in the cement composition layer 12 at the mounting positions of the embedded material 33 using a drill or the like. The mounting holes 45 have an opening in the lower surface 12a of the cement composition layer 12. After that, the mounting holes 45 are cleaned.

[0041] As shown in Figure 7(b), in the embedded material installation process (step S205), the anchor 46, which is the embedded material 33, is inserted into the installation hole 45, and then the anchor 46 is driven into the cement composition layer 12 using a hammer or the like. As a result, an enlarged diameter portion 46a that functions as an engaging portion 33a is formed near the upper end of the anchor 46.

[0042] In the locking material installation process (step S206), spacers 34 are placed at various locations so as to abut against the lower surface 12a of the cement composition layer 12. Then, with the mesh material 31 and the retaining material 35 in place, the stopper 36 is fastened to the anchor 46.

[0043] The operation and effects of the first embodiment will be described. (1-1) The fire-resistant structure 10 has an engaging portion 33a that engages with the cement composition layer 12, and a locking mechanism 30 that locks the fire-resistant coating layer 13 to the cement composition layer 12. By locking the fire-resistant coating layer 13 to the cement composition layer 12 via this locking mechanism 30, the fire resistance performance of the floor slab can be enhanced. Furthermore, since the degree of freedom regarding the thickness of the fire-resistant coating layer 13 is increased, even if it becomes necessary to improve the fire resistance performance of the floor slab after the initial design, this can be done by increasing the thickness of the fire-resistant coating layer 13. In other words, the fire resistance performance of the floor slab can be provided with fire resistance that takes into account the flammability of the contents of the lower floors.

[0044] (1-2) The fire-resistant coating layer 13 is formed by spray-on fire-resistant coating material. This allows the thickness of the fire-resistant coating layer 13 to be adjusted by the amount of spray-on fire-resistant coating material applied. As a result, the degree of freedom in the fire resistance performance that can be provided to the floor slab can be increased, and the thickness of the fire-resistant coating layer 13 can be easily increased.

[0045] (1-3) In the first example of the construction method, the locking mechanism 30 has an insert 40 that is attached to the bottom formwork 38 before the cement composition is poured. This eliminates the need to form mounting holes in the cement composition layer 12, thereby reducing the burden on workers associated with the installation of the locking mechanism 30.

[0046] (1-4) The locking mechanism 30 has a mesh material 31 that is joined to the insert 40. As a result, the fire-resistant coating layer 13 is formed in a state where it is intertwined with the mesh material 31, thereby increasing the locking force of the fire-resistant coating layer 13 by the locking mechanism 30.

[0047] (1-5) The locking mechanism 30 has a spacer 34 disposed between the cement composition layer 12 and the mesh material 31. This allows the gap between the cement composition layer 12 and the mesh material 31 to be maintained even when spraying the sprayed fire-resistant coating material. Furthermore, since the position of the mesh material 31 relative to the cement composition layer 12 can be adjusted by the thickness of the spacer 34, the mesh material 31 can be installed in a position suitable for the thickness of the fire-resistant coating layer 13.

[0048] (1-6) By constructing the mesh material 31 with a wire mesh that has a larger mesh size compared to metal mesh such as lath, more sprayed fire-resistant coating material can reach the inside of the mesh material 31, enabling reliable spraying up to the bottom surface 12a. As a result, strong adhesion between the floor slab and the fire-resistant coating can be expected.

[0049] (1-7) Wire mesh has higher rigidity than metal mesh such as lath. Therefore, by constructing the mesh material 31 with wire mesh, the mesh material 31 can be made less likely to bend during the construction process.

[0050] (1-8) According to the second example of the construction method, the locking mechanism 30 can be installed even after the cement composition has been poured. As a result, the degree of freedom of the floor slab to which the fire-resistant structure 10 can be applied can be increased.

[0051] (Second Embodiment) Referring to Figures 8 to 14, a second embodiment of the fire-resistant structure and the method for constructing the fire-resistant structure will be described. Note that the fire-resistant structure of the second embodiment has the same main components as the fire-resistant structure of the first embodiment. Therefore, in the second embodiment, the parts that differ from the first embodiment will be described in detail, and the same reference numerals will be used for components similar to those in the first embodiment, and their detailed descriptions will be omitted.

[0052] As shown in Figure 8, the fire-resistant structure 50 is applied to floor slabs where fire resistance is required. The fire-resistant structure 50 includes a steel formwork 51, a cement composition layer 12, a fire-resistant coating layer 13, and a locking mechanism 30.

[0053] The steel formwork 51 has a flat shape. The steel formwork 51 is composed of one or more metal flat plates. An example of a flat plate constituting the steel formwork 51 is a plate without irregularities. Another example of a flat plate constituting the steel formwork 51 is a plate with irregularities that do not contribute to the adhesion between the steel formwork 51 and the fire-resistant coating layer 13, for example, a plate with irregularities of 2.0 mm or less. In this embodiment, the steel formwork 51 uses a flat plate with irregularities of 2% or less relative to the plate thickness of the floor slab.

[0054] The cement composition layer 12 is placed on top of the steel formwork 51. The cement composition layer 12 is formed from cement composition that has hardened after being poured using the steel formwork 51 as the bottom formwork. Truss reinforcement bars 55 are embedded in the cement composition layer 12. The truss reinforcement bars 55 are fixed to the beams 16 that make up the building at their periphery via, for example, L-shaped connecting bars 56.

[0055] As shown in Figure 9, an example of a truss reinforcement 55 is composed of multiple truss units 60 and multiple upper-end reinforcement bars 69. The truss unit 60 includes a suspension member 61, a lattice member 62, an upper main reinforcement 63, and a lower main reinforcement 64. The lattice member 62, the upper main reinforcement 63, and the lower main reinforcement 64 extend in a first direction when viewed from above.

[0056] The suspension members 61 are arranged at predetermined intervals in a first direction. The suspension members 61 extend in a second direction perpendicular to the first direction when viewed from above. The suspension members 61 have an upper curved portion 65, a leg portion 66, and a joint portion 67.

[0057] The upper curved portion 65 has a convex shape that points upward. The leg portions 66 extend diagonally downward from each end of the upper curved portion 65. The joint portions 67 extend from the lower end of each leg portion 66 along the steel formwork 51. The joint portions 67 are the parts that are joined to the steel formwork 51. The upper main reinforcement bars 63 are joined to the upper curved portion 65 of the suspension member 61 from below.

[0058] In a side view, the lattice member 62 has a wave-like shape in which the upper folded portion and the lower folded portion are repeated at predetermined intervals. The upper folded portion of the lattice member 62 is joined to the upper main reinforcement 63. The joint between the lattice member 62 and the upper main reinforcement 63 is located below the joint between the upper curved portion 65 of the suspension member 61 and the upper main reinforcement 63. The lower folded portion of the lattice member 62 is joined to the lower main reinforcement 64. The ends of the upper main reinforcement 63 and the ends of the lower main reinforcement 64 are fixed to the beam 16 via connecting reinforcement 56.

[0059] The upper reinforcement bars 69 connect adjacent truss units 60. The upper reinforcement bars 69 extend in a second direction when viewed from above. The upper reinforcement bars 69 are arranged at predetermined intervals in the first direction and are joined to the upper end of the suspension member 61 from above.

[0060] As shown in Figure 10, the fire-resistant coating layer 13 is provided beneath the steel sacrificial formwork 51. The fire-resistant coating layer 13 covers the lower surface of the steel sacrificial formwork 51. The fire-resistant coating layer 13 is formed from a sprayed fire-resistant coating material that has been sprayed onto the steel sacrificial formwork 51 from below using a spraying machine and has hardened. In addition, in the locking mechanism 30, the spacer 34 of the locking material support 32 is fixed so as to abut against the steel sacrificial formwork 51.

[0061] (Construction method for the fire-resistant structure of the second embodiment) The construction method for fire-resistant structures will be explained with reference to Figures 11 to 14. In the construction method described below, the steel formwork 51 is delivered to the construction site with the truss reinforcement bars 55 already attached.

[0062] (First example of construction method in the second embodiment) As shown in Figure 11, in the first example of the construction method for the fire-resistant structure 50, the following steps are performed in order: steel formwork installation (step S301), mounting hole formation (step S302), embedded material installation (step S303), concrete pouring (step S304), locking material installation (step S305), and fire-resistant coating layer formation (step S306).

[0063] In the steel formwork installation process (step S301), the steel formwork 51 is installed by connecting the periphery of the truss reinforcement 55 to the beam 16 via connecting reinforcement 56. As shown in Figure 12(a), in the mounting hole formation step (step S302), mounting holes 70 are formed in the steel formwork 51 at the mounting positions for the embedded material 33 using a drill or the like. In the embedded material installation step (step S303), the insert 40, which is the embedded material 33, is attached to the steel formwork 51.

[0064] In the pouring process (step S304), after setting the side formwork in the predetermined position, the cement composition is poured using the steel sacrificial formwork 51 as the bottom formwork. The locking material installation process (step S305) is performed after the cement composition has been cured.

[0065] As shown in Figure 12(b), in the locking member installation process, spacers 34 are placed at various points so as to abut against the steel formwork 51, and then the mesh material 31 and the retaining material 35 are placed, and the stopper 36 is fastened to the insert 40. This attaches the mesh material 31 to the insert 40.

[0066] In the fire-resistant coating layer formation process (step S306), a spray coating material is sprayed onto the entire steel formwork 51 from the lower floor. Then, the fire-resistant coating layer 13 is formed as the spray coating material dries and hardens.

[0067] (Second example of construction method in the second embodiment) Referring to Figures 13 and 14, a second example of the construction method for the fire-resistant structure 50 will be described. This second example of the construction method can also be used when improvement of the fire resistance performance of the floor slab becomes necessary after the cement composition has been poured.

[0068] As shown in Figure 13, in the second example of the construction method for the fire-resistant structure 10, the following steps are performed in order: steel formwork installation (step S401), concrete casting (step S402), mounting hole formation (step S403), embedded material installation (step S404), locking material installation (step S405), and fire-resistant coating layer formation (step S406).

[0069] Note that the steel formwork installation process (step S401), the concrete casting process (step S402), and the fire-resistant coating layer formation process (step S406) are the same as those in the first example of the construction method. Therefore, here we will explain the mounting hole formation process (step S403), the embedded material installation process (step S404), and the locking material installation process (step S405).

[0070] As shown in Figure 14(a), the mounting hole formation process (step S403) is performed after the cement composition poured in the pouring process (step S402) has been cured. In the mounting hole formation process, first, mounting holes 71 of a predetermined depth are formed in the steel formwork 51 and the cement composition layer 12 at the mounting positions of the embedded material 33 using a drill or the like. After that, the mounting holes 71 are cleaned.

[0071] As shown in Figure 14(b), the embedded material 33 used in the second example of the construction method for the fire-resistant structure is a driven-in anchor 46. In the embedded material installation process (step S404), the anchor 46 is inserted into the installation hole 71, and then driven into the cement composition layer 12 using a hammer or the like.

[0072] In the locking material installation process (step S405), the stopper 36 is fastened to the anchor 46 with the spacer 34, mesh material 31, and retaining material 35 positioned at various locations.

[0073] According to this second embodiment of the fire-resistant structure 50, effects and benefits similar to those described in (1-1) to (1-8) of the first embodiment can be obtained. The first and second embodiments can be implemented with the following modifications. The first and second embodiments and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0074] In the first example of the construction method in the first embodiment, the mounting hole formation step (step S102) may be performed before the formwork installation step (step S101). In this case, the embedded material installation step (step S103) may be performed between the mounting hole formation step and the formwork installation step.

[0075] In the first example of the construction method in the second embodiment, the mounting hole formation step (step S302) may be performed before the steel formwork installation step (step S301). In this case, the embedded material installation step (step S303) may be performed between the mounting hole formation step and the steel formwork installation step.

[0076] The mesh material 31 can be made of mesh. Therefore, the mesh material 31 is not limited to being made of wire mesh, but may also be made of lath or other materials with relatively fine mesh. The locking mechanism 30 is not limited to a configuration having a mesh material 31. For example, the locking mechanism 30 may have a configuration in which a flat plate material larger than the head of the stopper 36 is used as a locking material instead of the mesh material 31 and the retaining material 35. In this case, the flat plate material is preferably large enough to allow spray-on fire-resistant coating material to be sprayed from the lower floor into the space between it and the cement composition layer 12 or the steel formwork 51. The flat plate material may also be provided with loop-shaped, hook-shaped, or rod-shaped projections. Alternatively, for example, the locking mechanism 30 may be composed of the embedded material 33 and the stopper 36, by using a bolt with a washer, to which a washer of a certain size is integrally connected, as the stopper 36.

[0077] The embedded material 33, the insert 40, is attached to the bottom formwork before the cement composition is poured, and only needs to have a flange portion 40a and a female threaded portion at its lower end; it is not limited to having a spring 41.

[0078] In floor slabs to which the fire-resistant structure 50 is applied, the steel formwork 51 is not limited to flat steel plates, but may also be steel plates with various types of irregularities. Furthermore, the truss reinforcement is not limited to the truss reinforcement 55 with the configuration shown in Figure 9, but various types of truss reinforcement can be used.

[0079] The floor slab to which the fire-resistant structure 50 is applied only needs to have a steel formwork 51 and a cement composition layer 12, and may be a floor slab in which truss reinforcement 55 is not embedded in the cement composition layer 12. Alternatively, it may be a floor slab in which various types of reinforcement are embedded in the cement composition layer 12.

[0080] The fire-resistant structure 50 only needs to have a steel formwork 51, a cement composition layer 12, a fire-resistant coating layer 13, and a locking mechanism 30. Therefore, the fire-resistant structure 50 is not limited to floor slabs, but can be applied to horizontal structural members that extend horizontally, such as beams.

[0081] The floor slab to which the fire-resistant structure 10 is applied only needs to have a cement composition layer 12, and may be a floor slab in which various reinforcing bars are not embedded in the cement composition layer 12. Furthermore, the fire-resistant structure 10 only needs to have a cement composition layer 12, a fire-resistant coating layer 13, and a locking mechanism 30. Therefore, the fire-resistant structure 10 can be applied to horizontal structural members that extend horizontally, such as beams. The same applies to the fire-resistant structure 50. [Explanation of symbols]

[0082] 10...Fire-resistant structure, 12...Cement composition layer, 12a...Bottom surface, 13...Fire-resistant coating layer, 16...Beam, 21...Upper main reinforcement, 22...Lower main reinforcement, 30...Locking mechanism, 31...Mesh material as locking material, 32...Locking material support, 33...Embedded material, 33a...Engaging part, 34...Spacer, 35...Pressing material, 36...Stopper, 38...Bottom formwork, 39...Mounting hole, 40...Insert as embedded material, 40a...Flange part as engaging part, 41...Sp Ring, 42...Support plate, 43...Temporary fastening bolt, 44...Temporary fastening part, 45...Mounting hole, 46...Anchor as embedded material, 46a...Enlarged diameter part as engaging part, 50...Fire-resistant structure, 51...Steel disposable formwork, 55...Truss reinforcement, 56...Connecting reinforcement, 60...Truss unit, 61...Hanging member, 62...Lattice member, 63...Upper end main reinforcement, 64...Lower end main reinforcement, 65...Upper end curved part, 66...Legs, 67...Joint, 69...Upper end distribution reinforcement, 70, 71...Mounting holes.

Claims

1. A cement composition layer, A fire-resistant coating layer is provided below the cement composition layer, It has an engaging portion that engages with the cement composition layer, and a locking mechanism that locks the fire-resistant coating layer to the cement composition layer, The aforementioned locking mechanism is An embedded material having the aforementioned engaging portion and embedded in the cement composition layer, It is composed of a bolt with a washer, which is joined to the embedded material and has a washer portion that is positioned away from the cement composition layer to secure the fire-resistant coating layer. Fireproof construction.

2. There is no structural steel plate between the cement composition layer and the fire-resistant coating layer. The fire-resistant structure according to claim 1.

3. Between the cement composition layer and the fire-resistant coating layer, there is a steel formwork, The washer portion is positioned away from the steel formwork. The fire-resistant structure according to claim 1.

4. The aforementioned fire-resistant coating layer is a spray-applied fire-resistant coating material. The fire-resistant structure according to any one of claims 1 to 3.

5. A cement composition layer, A method for constructing a fire-resistant structure applied to a horizontal structural member extending in the horizontal direction, comprising a fire-resistant coating layer provided below the cement composition layer, A mounting hole forming step in which mounting holes are formed in the bottom formwork, A buried material installation step involves installing a buried material into the aforementioned mounting hole, A pouring step of pouring a cement composition into the bottom formwork so that the buried material is buried, A locking material installation step involves attaching a bolt with a washer, which has a washer portion for locking the fire-resistant coating layer, to the embedded material embedded in the cement composition layer, such that the washer portion is positioned away from the cement composition layer. The process includes a step of forming a fire-resistant coating layer, in which a fire-resistant coating material is sprayed toward the cement composition layer so that the washer portion is embedded. Construction methods for fire-resistant structures.

6. A cement composition layer, A method for constructing a fire-resistant structure applied to a horizontal structural member extending in the horizontal direction, comprising a fire-resistant coating layer provided below the cement composition layer, The pouring process involves pouring the cement composition into the bottom formwork, A mounting hole forming step in which mounting holes are formed in the cement composition layer, The embedding material installation step involves inserting a drive-in type embedding material into the aforementioned mounting hole and driving the embedding material into the cement composition layer, A locking material installation step involves attaching a bolt with a washer, which has a washer portion for locking the fire-resistant coating layer, to the embedded material driven into the cement composition layer, such that the washer portion is positioned away from the cement composition layer. The process includes a step of forming a fire-resistant coating layer, in which a fire-resistant coating material is sprayed toward the cement composition layer so that the washer portion is embedded. Construction methods for fire-resistant structures.

7. The bottom formwork is a wooden formwork that is removed after the pouring process, or a steel disposable formwork that is left embedded. A method for constructing a fire-resistant structure according to claim 5 or 6.

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