Fire-resistant structure of wood-steel joint portion

Abstract

To provide a versatile fire-resistant structure of a wood-steel joint portion between a wooden member and a steel member.SOLUTION: A fire-resistant structure of a joint portion between a wooden member 12 and a steel member 14 comprises: a cutout portion 22 provided on a surface of the wooden member 12, in which a part of the steel member 14 is placed; and a moisture-containing inorganic fire-resistant material 24 filled and placed in the cutout portion 22 so as to cover a periphery of the steel member 14 in order to reduce heat input from the steel member 14 to the wooden member 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fire-resistant structure of a wood-steel joint, which is a joint between a wood member and a steel member.

Background Art

[0002] Conventionally, in order to achieve carbon neutrality in the construction field, the utilization of wood members has been promoted. Under such circumstances, in large-scale buildings, there are many cases of adopting a hybrid structure that combines wood members and steel members. Generally, steel members are provided with a fire-resistant coating that allows a temperature rise up to about 500°C during a fire, while wood members may undergo carbonization and combustion at about 260°C. Therefore, in the case of a hybrid structure that requires fire resistance, the joint between the wood member and the steel member (wood-steel joint) requires a structure that reduces the heat input from the steel member so that the temperature of the wood member does not exceed 260°C.

[0003] As a conventional technique of such a structure, for example, a method of applying a fire-resistant coating material such that the temperature of the steel member at the joint does not exceed 260°C (see, for example, Patent Document 1), or a method of providing a fire-resistant portion with a fire-resistant coating thickness thicker than normal between the wood member and the steel member to reduce the heat input from the steel member (see, for example, Patent Document 2) has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a beam string structure used for a large roof of a large building, there is a joint where a steel bundled material, a lower chord member, and a support penetrate directly into a wooden upper chord beam. On the other hand, since the above prior art targets a joint where a wooden member and a steel member are adjacent, it is difficult to directly apply it to the joint in the beam string structure. Further, in the above prior art, it is necessary to make the thickness of the fire-resistant coating material in the vicinity of the joint considerably thicker than that of the general part, and there is also a problem that a design limitation occurs.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a fire-resistant structure for a wooden-steel joint of a wooden member and a steel member having excellent versatility.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, a fire-resistant structure for a wooden-steel joint according to the present invention is a fire-resistant structure for a joint of a wooden member and a steel member, and is provided on the surface of the wooden member, and a recessed portion in which a part of the steel member is disposed, and in order to reduce heat transfer from the steel member to the wooden member, it is filled and disposed in the recessed portion so as to cover the periphery of the steel member, and is characterized by comprising an inorganic fire-resistant material containing moisture.

[0008] Further, another fire-resistant structure for a wooden-steel joint according to the present invention is characterized by further comprising a dropout prevention material for preventing dropout of the fire-resistant material from the recessed portion in the above-described invention.

[0009] Further, another fire-resistant structure for a wooden-steel joint according to the present invention is characterized in that in the above-described invention, a fire-resistant coating material is provided on the surface of the wooden member, a joint portion is provided in the fire-resistant coating material at a position corresponding to the recessed portion, and a non-combustible material or an inorganic sealing material and a sealing material having fire-resistant performance are filled and disposed between the joint portion and the steel member.

[0010] In addition, in the refractory structure of another wooden-steel joint according to the present invention, in the above-described invention, a refractory coating material is provided on the surface of the wooden member, a joint portion is provided in the refractory coating material at a position corresponding to the recessed portion, and a refractory paint is provided on the surface of the steel member at a position corresponding to the joint portion.

[0011] In addition, in the refractory structure of another wooden-steel joint according to the present invention, in the above-described invention, the wooden member is a beam member, and the steel member is a steel support, a steel tie member, or a steel lower chord member disposed on the lower surface side of the wooden member.

Advantages of the Invention

[0012] According to the refractory structure of the wooden-steel joint according to the present invention, it is a refractory structure of the joint portion between the wooden member and the steel member, and includes a recessed portion provided on the surface of the wooden member and in which a part of the steel member is disposed, and an inorganic refractory material containing moisture, which is filled and disposed in the recessed portion so as to cover the periphery of the steel member, in order to reduce the heat input from the steel member to the wooden member. Therefore, the heat input from the steel member to the wooden member can be reduced by the endothermic action accompanying the evaporation of the moisture of the refractory material filled and disposed in the recessed portion, and the temperature of the wooden member can be suppressed. In addition, it can be widely applied to the joint portion provided with the recessed portion and has excellent versatility. Therefore, it is possible to provide a refractory structure of a wooden-steel joint having excellent versatility.

[0013] In addition, according to the refractory structure of another wooden-steel joint according to the present invention, since it further includes a dropout prevention material for preventing the dropout of the refractory material from the recessed portion, it is possible to prevent the dropout of the refractory material from the recessed portion.

[0014] In addition, according to the refractory structure of another wooden-steel joint according to the present invention, a refractory coating material is provided on the surface of the wooden member, a joint portion is provided in the refractory coating material at a position corresponding to the recessed portion, and a non-combustible material or an inorganic sealing material and a sealing material having refractory performance are filled and disposed between the joint portion and the steel member. Therefore, it is possible to ensure the refractory performance of the joint portion.

[0015] Further, according to another fire-resistant structure of the wooden-steel joint according to the present invention, a fire-resistant coating material is provided on the surface of the wooden member, a joint portion is provided on the fire-resistant coating material at a position corresponding to the recessed portion, and a fire-resistant paint is provided on the surface of the steel member at a position corresponding to the joint portion, so that the fire-resistant performance of the joint portion can be ensured.

[0016] Further, according to another fire-resistant structure of the wooden-steel joint according to the present invention, the wooden member is a beam member, and the steel member is a steel support, a steel tie or a steel lower chord member disposed on the lower surface side of the wooden member, so that the fire-resistant performance of the joint between the wooden member and the steel support, the steel tie or the steel lower chord member in the cable-stayed beam can be ensured.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the fire-resistant structure of the wooden-steel joint according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by this embodiment.

[0019] First, the bowstring beam to which the fire-resistant structure of the wooden-steel joint according to the embodiment of the present invention is applied will be described. As shown in FIG. 1, this bowstring beam 10 includes an upper chord beam 12 (beam member) made of an arch-shaped wooden member, a bundled member 14 (steel bundled member) made of a steel member disposed on the lower surface side of the upper chord beam 12, and a lower chord member 16 (steel lower chord member). The upper chord beam 12 is installed on a support 20 (steel support) provided at the top of the column head 18. The mating portion between the upper chord beam 12 and the bundled member 14 is the joint A, the mating portion between the upper chord beam 12 and the lower chord member 16 is the joint B, and the mating portion between the upper chord beam 12 and the support 20 is the joint C. This embodiment is applied to the joints A to C. Note that the application target of the present invention is not limited to the joints in the bowstring beam 10, and it can be widely applied to joints of other structures as well.

[0020] Next, Embodiments 1 to 3 of the present invention applied to the above joints A to C will be described.

[0021] (Embodiment 1) First, Embodiment 1 of the present invention will be described. Embodiment 1 corresponds to the joint A between the upper chord beam 12 and the bundled member 14. FIG. 2(1) is a side sectional view showing Embodiment 1, (2) is a schematic view of the dimensions of the specimen used in the fire resistance test, and (3) is a view showing the fire resistance test results.

[0022] As shown in FIG. 2(1), the fire-resistant structure 100 of the wooden-steel joint according to Embodiment 1 includes a recessed portion 22 provided on the lower surface of the upper chord beam 12 and in which a part of the bundled member 14 is disposed, and a cement mortar 24 filled and disposed in the recessed portion 22 so as to cover the periphery of the bundled member 14 in order to reduce the heat transfer from the bundled member 14 to the upper chord beam 12. The cement mortar 24 is an inorganic fire-resistant material containing moisture.

[0023] The upper chord beam 12 is a wooden member having fire resistance and extending in a substantially horizontal direction, and includes a core material 26 made of laminated wood that bears the load, and a fire-resistant coating material 28 disposed on the outer surface of the core material 26. The cross-sectional shape of the core material 26 is assumed to be rectangular, but it is not limited thereto. The fire-resistant coating material 28 can be configured using, for example, reinforced gypsum board or a fire-resistant sheet that foams upon heating to exhibit heat insulation properties. A decorative material made of a wooden material may be attached to the outside of the fire-resistant coating material 28. In the first embodiment, it is assumed that the thickness of the fire-resistant coating material 28 is about several centimeters, but the present invention is not limited thereto.

[0024] The bundled material 14 includes a small-diameter bar-shaped steel material 30 extending vertically downward from the recessed portion 22, and a fire-resistant paint 32 provided on the surface of the steel material 30. A tip portion 34 having a smaller diameter than the lower end side is provided on the upper end side of the bundled material 14. The fire-resistant paint 32 is not provided on the surface of the tip portion 34. The tip portion 34 is disposed in the recessed portion 22.

[0025] The fire-resistant paint 32 is a foaming type that foams and thickens upon heating. For example, a fire-resistant paint mainly composed of ammonium polyphosphate can be used. In such a fire-resistant paint, when heated during a fire, foaming starts at around 250°C, foams 20 to 30 times to form a heat-insulating layer, and suppresses the temperature rise of the steel material 30. The fire-resistant paint 32 is preferably pre-coated (pre-painted) on the surface of the steel material 30 at a predetermined thickness in a factory or the like in advance. In the first embodiment, it is assumed that the diameter of the steel material 30 is about several centimeters and the thickness of the fire-resistant paint 32 is about several millimeters to several tens of millimeters, but the present invention is not limited thereto.

[0026] The recessed portion 22 is a portion where the lower surface of the upper chord beam 12 is cut out in a concave shape. The recessed portion 22 is configured by connecting an upper recessed portion 36 formed in the core material 26 and a lower recessed portion 38 formed in the fire-resistant coating material 28 vertically. The upper recessed portion 36 is composed of a coaxial cylindrical large-diameter cavity with the bundled material 14, and the lower recessed portion 38 is composed of a small-diameter cavity. Note that the shape of the recessed portion 22 may be other shapes, for example, a shape in which prismatic cavities are connected vertically.

[0027] In the upper recessed portion 36, the upper part 40 of the tip portion 34 of the bundled material 14 is penetrated and arranged, and cement mortar 24 is filled and arranged around the upper part 40. Therefore, the cement mortar 24 covers the periphery of the upper part 40 of the tip portion 34 of the bundled material 14. In the lower recessed portion 38, the lower part 42 of the tip portion 34 of the bundled material 14 is penetrated and arranged, and the non-combustible material 44 and the fireproof sealing material 46 are laminated and arranged in order from above. The non-combustible material 44 and the fireproof sealing material 46 are filled and arranged between the lower part 42 of the tip portion 34 and the end portion of the fireproof coating material 28. For the non-combustible material 44, for example, rock wool felt or the like can be used. Note that, instead of the non-combustible material 44, an inorganic sealing material may be used. For the fireproof sealing material 46, for example, a sealing material having fireproof performance such as a modified silicone-based sealing material or an inorganic-based sealing material can be used.

[0028] It is preferable that the cement mortar 24 is placed and constructed in the recessed portion 22 provided in advance in the upper chord beam 12 in a state where the bundled material 14 is installed at a predetermined position. A dropout prevention material for preventing the dropout of the cement mortar 24 from the recessed portion 22 may be provided. In this way, the dropout of the cement mortar 24 from the recessed portion 22 can be prevented.

[0029] The fireproof coating material 28 is preferably installed by notching the portion through which the bundled material 14 penetrates. Further, a joint portion (corresponding to the lower recessed portion 38) may be provided in the fireproof coating material 28 at the joint portion between the fireproof coating material 28 and the bundled material 14. In this way, the workability can be improved. The angle of the joint portion is not particularly limited. It is desirable to fill the joint portion with the non-combustible material 44 and then seal it with the fireproof sealing material 46. In this way, the fireproof performance of the joint portion can be ensured. A fireproof paint 32 may be provided on the surface of the bundled material 14 at the position corresponding to the joint portion. In this way, the fireproof performance of the joint portion can be improved.

[0030] According to the first embodiment, the bundled material 14 is joined to the wooden upper chord beam 12 via the cement mortar 24. Mainly due to the endothermic effect accompanying the evaporation of the moisture in the cement mortar 24, the heat input from the bundled material 14 can be reduced, and the temperature of the upper chord beam 12 can be suppressed below the carbonization temperature. Thereby, the fire resistance performance of the joint A in the arch-supported beam 10 can be ensured. In addition, the thickness of the fireproof coating material 28 in the vicinity of the joint can be made the same as that of the general part other than the joint, resulting in a simplified arrangement of only wood and steel. For this reason, it is possible to realize a specification design of a wood-steel joint excellent in designability.

[0031] Also, during construction, since the upper chord beam 12 and the bundled material 14 are joined via the recessed portion 22 with the cement mortar 24 which is in an amorphous state, it is applicable regardless of the shape of the bundled material 14, and has high versatility. For this reason, the first embodiment can be widely applied to joints provided with the recessed portion 22 and is excellent in versatility. Therefore, it is possible to provide a fire-resistant structure for a wood-steel joint excellent in versatility.

[0032] Regarding the above fire-resistant structure 100, the experimental results when a fire resistance experiment was conducted on the test piece in Fig. 2(2) are shown in Fig. 2(3). In the experiment, the test piece was installed in the furnace, heated for 1 hour according to the heating curve defined in ISO834-1, and the temperatures at the temperature measurement positions T1 and T2 were measured. After the heating was completed, the test piece was allowed to cool in the furnace.

[0033] As a result, as shown in Fig. 2(3), while the temperature of the bundled material 14 rises to about 550°C, the maximum of the boundary temperature between the cement mortar 24 and the wooden upper chord beam 12 is about 100°C, and carbonization and combustion of the upper chord beam 12 did not occur. From the above, it was confirmed that the fire-resistant structure of this example has a predetermined fire resistance performance.

[0034] (Second Embodiment) Next, a second embodiment of the present invention will be described. The second embodiment corresponds to the joint B between the upper chord beam 12 and the lower chord member 16. Fig. 3(1) is a side sectional view showing the second embodiment, (2) is a schematic view of the dimensions of the test piece used for the fire resistance experiment, (3) is a sectional view taken along the line A-A of (2), and (4) is a view showing the fire resistance experiment results.

[0035] As shown in Fig. 3(1), the fire-resistant structure 200 of the wooden steel joint according to the second embodiment is provided on the lower surface of the upper chord beam 12, and includes a recess 48 where a part of the lower chord member 16 is arranged, and cement mortar 24 filled and arranged in the recess 48 so as to cover the periphery of the lower chord member 16 in order to reduce the heat input from the lower chord member 16 to the upper chord beam 12. The cement mortar 24 is an inorganic fire-resistant material containing moisture.

[0036] The upper chord beam 12 is a wooden member having fire-resistant performance extending in a substantially horizontal direction, and includes a core material 26 made of laminated wood that bears the load, and a fire-resistant coating material 28 arranged on the outer surface of the core material 26. Since the upper chord beam 12 has the same configuration as that described in the first embodiment above, a specific description thereof is omitted.

[0037] The lower chord member 16 includes a thin-diameter bar-shaped steel material 30 extending obliquely with respect to the horizontal, and a fire-resistant coating 32 provided on the surface of the steel material 30. Since the fire-resistant coating 32 has the same configuration as that described in the first embodiment above, a specific description thereof is omitted. The lower chord member 16 penetrates the upper chord beam 12 in an obliquely up-and-down direction. The upper side of the lower chord member 16 protrudes obliquely upward from the upper surface of the upper chord beam 12 and is fixed and fire-resistant coated with a fire-resistant coating material. The lower side of the lower chord member 16 protrudes obliquely downward from the recess 48. Inside the core material 26 and the recess 48, the fire-resistant coating 32 is not provided on the surface of the lower chord member 16.

[0038] The recess 48 is a portion obtained by notching the lower surface of the upper chord beam 12 in a concave shape. The recess 48 is configured by connecting an upper recess 50 formed in the core material 26 and a lower recess 52 formed in the fire-resistant coating material 28 vertically. The upper recess 50 is composed of a small rectangular parallelepiped-shaped cavity, and the lower recess 52 is composed of a cylindrical cavity that is coaxial with the lower chord member 16 and slightly larger in diameter than the lower chord member 16. Note that the shape of the recess 48 may be other shapes.

[0039] In the upper recessed portion 50, the lower chord member 16 is disposed to penetrate obliquely from the lower central portion toward the upper corner portion, and cement mortar 24 is filled and disposed around the lower chord member 16. In the lower recessed portion 52, the lower chord member 16 is disposed to penetrate obliquely upward from below, and the non-combustible material 44 and the fire-resistant sealing material 46 are laminated and disposed in order from above around the lower chord member 16. The non-combustible material 44 and the fire-resistant sealing material 46 are filled and disposed between the lower chord member 16 and the end portion of the fire-resistant coating material 28. Since the non-combustible material 44 and the fire-resistant sealing material 46 have the same configuration as those described in the above Embodiment 1, a specific description thereof is omitted.

[0040] The cement mortar 24 is preferably placed and constructed in a recessed portion 48 provided in advance in the upper chord beam 12 in a state where the lower chord member 16 is installed at a predetermined position. A dropout prevention material for preventing the cement mortar 24 from dropping out of the recessed portion 48 may be provided. In this way, the dropout of the cement mortar 24 from the recessed portion 48 can be prevented.

[0041] The fire-resistant coating material 28 is preferably installed by cutting out a portion through which the lower chord member 16 penetrates. Further, a joint portion (corresponding to the lower recessed portion 52) may be provided in the fire-resistant coating material 28 at the joint portion between the fire-resistant coating material 28 and the lower chord member 16. In this way, the workability can be improved. The angle of the joint portion is not particularly limited. It is desirable to fill the joint portion with the non-combustible material 40 and then seal it with the fire-resistant sealing material 42. In this way, the fire-resistant performance of the joint portion can be ensured. A fire-resistant paint 32 may be provided on the surface of the lower chord member 16 at a position corresponding to the joint portion. In this way, the fire-resistant performance of the joint portion can be improved.

[0042] According to the second embodiment, the lower chord member 16 is joined to the wooden upper chord beam 12 via the cement mortar 24. Mainly due to the heat absorption effect associated with the evaporation of the moisture in the cement mortar 24, the heat input from the lower chord member 16 can be reduced, and the temperature of the upper chord beam 12 can be suppressed below the carbonization temperature. Thereby, the fire resistance performance of the joint B in the arch-supported beam 10 can be ensured. In addition, the thickness of the fireproof coating material 28 near the joint can be made the same as that of the general part other than the joint, resulting in a simplified arrangement of only wood and steel. Therefore, it is possible to realize a specification design of a wood-steel joint with excellent design properties.

[0043] Also, during construction, since the upper chord beam 12 and the lower chord member 16 are joined via the recessed part 48 by the cement mortar 24 which is in an amorphous state, it is applicable regardless of the shape of the lower chord member 16 and has high versatility. Therefore, the second embodiment can be widely applied to joints provided with the recessed part 48 and is excellent in versatility. Accordingly, it is possible to provide a fire-resistant structure for a wood-steel joint with excellent versatility.

[0044] Regarding the above fire-resistant structure 200, the experimental results when a fire resistance test was conducted on the test specimens shown in FIGS. 3(2) and (3) are shown in FIG. 3(4). In the experiment, the test specimens were installed in the furnace, heated for 1 hour according to the heating curve defined in ISO834-1, and the temperatures were measured at the temperature measurement positions T1 and T2. After the heating was completed, the test specimens were allowed to cool in the furnace.

[0045] As a result, as shown in FIG. 3(4), while the temperature of the lower chord member 16 rises to about 550°C, the maximum of the boundary temperature between the cement mortar 24 and the wooden upper chord beam 12 is about 100°C and levels off, and carbonization and combustion of the upper chord beam 12 did not occur. From the above, it was confirmed that the fire-resistant structure of this example has a predetermined fire resistance performance.

[0046] (Embodiment 3) Next, Embodiment 3 of the present invention will be described. Embodiment 3 of the present invention corresponds to the joint C between the upper chord beam 12 and the support 20. FIG. 4(1) is a side sectional view showing Embodiment 3, (2) is a schematic diagram of the dimensions of the test specimen used for the fire resistance test, (3) is a sectional view taken along line A-A of (2), and (4) is a diagram showing the fire resistance test results.

[0047] As shown in Fig. 4(1), the fireproof structure 300 of the wooden-steel joint according to the third embodiment is provided on the lower surface of the upper chord beam 12, and includes a recessed portion 54 where the upper part of the support 20 is arranged, and cement mortar 24 filled and arranged in the recessed portion 54 so as to cover the periphery of the support 20 in order to reduce the heat transfer from the support 20 to the upper chord beam 12. The cement mortar 24 is an inorganic fireproof material containing moisture.

[0048] The upper chord beam 12 is a wooden member having fireproof performance extending in a substantially horizontal direction, and includes a core material 26 made of laminated wood that bears the load, and a fireproof coating material 28 arranged on the outer surface of the core material 26. Since the upper chord beam 12 has the same configuration as that described in the first embodiment above, a specific description thereof is omitted.

[0049] The support 20 includes a steel material 30 constituting a steel pin support, and a fireproof coating 32 provided on the surface of the steel material 30. Since the fireproof coating 32 has the same configuration as that described in the first embodiment above, a specific description thereof is omitted. A tapered portion 56 whose width expands as it goes upward is provided on the upper part of the support 20. A plate 58 extending in a substantially horizontal direction is provided at the upper end of the tapered portion 56, and a plurality of studs 60 project from the upper surface of the plate 58. The fireproof coating 32 is not provided on the surfaces of the plate 58 and the studs 60. The tapered portion 56, the plate 58, and the studs 60 are arranged in the recessed portion 54. Note that the shape of the support 20 is an example, and the shape of the support in the present invention is not limited thereto.

[0050] The recessed portion 54 is a portion formed by notching the lower surface of the upper chord beam 12 in a concave shape. The recessed portion 54 is configured by connecting an upper recessed portion 62 formed in the core material 26 and a lower recessed portion 64 formed in the fireproof coating material 28 vertically. The upper recessed portion 62 is composed of a small rectangular parallelepiped-shaped cavity, and the lower recessed portion 64 is composed of a groove-shaped cavity. It is composed of a groove-shaped cavity slightly larger than the tapered portion 56. Note that the shape of the recessed portion 54 may be other shapes.

[0051] In the upper recessed portion 62, the plate 58 and the stud 60 of the support 20 are penetrated and arranged, and cement mortar 24 is filled and arranged around the plate 58 and the stud 60. In the lower recessed portion 64, the tapered portion 56 of the support 20 is penetrated and arranged from below, and the non-combustible material 44 and the fireproof sealing material 46 are laminated and arranged in order from above around the tapered portion 56. The non-combustible material 44 and the fireproof sealing material 46 are filled and arranged between the tapered portion 56 of the support 20 and the end portion of the fireproof coating material 28. Since the non-combustible material 44 and the fireproof sealing material 46 have the same configuration as those described in the above Embodiment 1, the specific description thereof is omitted.

[0052] It is preferable that the cement mortar 24 is placed and constructed in the recessed portion 54 provided in advance in the upper chord beam 12 in a state where the support 20 is installed at a predetermined position. A dropout prevention material for preventing the cement mortar 24 from dropping out of the recessed portion 54 may be provided. In this way, the dropout of the cement mortar 24 from the recessed portion 54 can be prevented.

[0053] It is preferable that the fireproof coating material 28 is installed by cutting out the portion through which the support 20 penetrates. Further, a joint portion (corresponding to the lower recessed portion 64) may be provided in the fireproof coating material 28 at the mating portion between the fireproof coating material 28 and the support 20. In this way, the workability can be improved. The angle of the joint portion is not particularly limited. It is desirable to fill the joint portion with the non-combustible material 40 and then seal it with the fireproof sealing material 42. In this way, the fireproof performance of the joint portion can be ensured. A fireproof paint 32 may be provided on the surface of the support 20 at the position corresponding to the joint portion. In this way, the fireproof performance of the joint portion can be improved.

[0054] According to the third embodiment, the support 20 is joined to the wooden upper chord beam 12 via the cement mortar 24. Mainly due to the endothermic effect associated with the evaporation of moisture in the cement mortar 24, the heat input from the support 20 can be reduced, and the temperature of the upper chord beam 12 can be suppressed below the carbonization temperature. Thereby, the fire resistance performance of the joint C in the cable-stayed beam 10 can be ensured. In addition, the thickness of the fireproof coating material 28 near the joint can be made the same as that of the general part other than the joint, resulting in a simplified arrangement of only wood and steel. Therefore, a specification design of a wood-steel joint with excellent design quality can be realized.

[0055] Also, during construction, since the upper chord beam 12 and the support 20 are joined via the recessed part 54 by the cement mortar 24 which is in an amorphous state, it is applicable regardless of the shape of the support 20, and has high versatility. Therefore, the third embodiment can be widely applied to joints provided with the recessed part 54 and has excellent versatility. Thus, a fire-resistant structure of a wood-steel joint with excellent versatility can be provided.

[0056] Regarding the above fire-resistant structure 300, the experimental results when a fire resistance test was conducted on the test specimens shown in FIGS. 4(2) and (3) are shown in FIG. 4(4). In the experiment, the test specimens were installed in the furnace, heated for 1 hour according to the heating curve defined in ISO834-1, and the temperatures were measured at the temperature measurement positions T1 and T2. After the heating was completed, the test specimens were allowed to cool in the furnace.

[0057] As a result, as shown in FIG. 4(3), while the temperature of the support 20 rises to about 450°C, the maximum of the boundary temperature between the cement mortar 24 and the wooden upper chord beam 12 is about 160°C, and carbonization and combustion of the upper chord beam 12 did not occur. From the above, it was confirmed that the fire-resistant structure of this example has the predetermined fire resistance performance.

[0058] (Modification example) Next, modification examples of the above-described first to third embodiments will be described.

[0059] First, a modification example of the first embodiment of the present invention will be described. As shown in Fig. 5(1), the fire-resistant structure 101 of the wooden-steel joint according to this modification is such that steel screws 66 (anti-drop-off material) are penetrated and arranged from the upper recessed portion 36 into the core material 26. By doing so, it is possible to prevent the cement mortar 24 from dropping off from the upper recessed portion 36.

[0060] Also, a bolt-type steel bar 68 is arranged in the upper recessed portion 36, and the bundled material 14 is connected via this steel bar 68. The head 70 of the steel bar 68 is arranged in the upper recessed portion 36, and the shaft portion 72 of the steel bar 68 protrudes downward from the lower recessed portion 38. A thread groove is formed on the lower end side of the shaft portion 72, and a nut 74 is screwed thereon. On the other hand, the upper end side of the bundled material 14 has a hollow structure, and a nut 76 is fixed to the upper end portion thereof. The bundled material 14 is fitted into the lower end of the shaft portion 72 and fastened and fixed by nuts 74 and 76.

[0061] In this structure, since it can be constructed by a method of inserting the bundled material 14 into the shaft portion 72 of the steel bar 68, the workability can be improved. Also, a columnar cement mortar 24 having a built-in steel bar 68 may be penetrated into the upper recessed portion 36 of the upper chord beam 12 in advance. By doing so, the workability is further improved.

[0062] Next, a modification of Embodiment 2 of the present invention will be described. As shown in Fig. 5(2), the fire-resistant structure 201 of the wooden-steel joint according to this modification is such that steel screws 66 (anti-drop-off material) are penetrated and arranged from the upper recessed portion 50 into the core material 26. By doing so, it is possible to prevent the cement mortar 24 from dropping off from the upper recessed portion 50.

[0063] Further, the lower chord member 16 is composed of an upper upper chord member 78 and a lower lower chord member 80. The upper upper chord member 78 is disposed through the upper chord beam 12, and the lower lower chord member 80 is connected to the lower end of the upper upper chord member 78. The lower end of the upper upper chord member 78 protrudes downward from the lower notch portion 52. A screw groove is formed on the lower end side of the upper upper chord member 78, and a nut 82 is screwed thereon. On the other hand, the upper end side of the lower lower chord member 80 has a hollow structure, and a nut 84 is fixed to the upper end portion thereof. The lower lower chord member 80 is fitted into the lower end of the upper upper chord member 78 and fastened and fixed by nuts 82 and 84. With this structure, since the construction can be carried out by a method of inserting the lower lower chord member 80 into the upper upper chord member 78, the workability can be improved.

[0064] Next, a modified example of Embodiment 3 of the present invention will be described. As shown in FIG. 5(3), the fire-resistant structure 301 of the wooden-steel joint according to this modified example is such that steel screws 66 (anti-drop-off materials) are penetrated and arranged from the upper notch portion 62 into the core material 26. In this way, it is possible to prevent the cement mortar 24 from dropping off from the upper notch portion 62.

[0065] As described above, according to the fire-resistant structure of the wooden-steel joint according to the present invention, it is a fire-resistant structure of the joint portion between the wooden member and the steel member, which is provided on the surface of the wooden member, and has a notch portion in which a part of the steel member is disposed, and in order to reduce the heat input from the steel member to the wooden member, it is filled and arranged in the notch portion so as to cover the periphery of the steel member, and an inorganic fire-resistant material containing moisture. Therefore, the heat input from the steel member to the wooden member can be reduced by the heat absorption action accompanying the evaporation of the moisture of the fire-resistant material filled and arranged in the notch portion, and the temperature of the wooden member can be suppressed. In addition, it can be widely applied to the joint portion provided with the notch portion, and has excellent versatility. Therefore, it is possible to provide a fire-resistant structure of a wooden-steel joint having excellent versatility.

[0066] Further, according to another fire-resistant structure of the wooden-steel joint according to the present invention, since it further includes an anti-drop-off material for preventing the drop-off of the fire-resistant material from the notch portion, the drop-off of the fire-resistant material from the notch portion can be prevented.

[0067] Further, according to the fire-resistant structure of another wooden-steel joint according to the present invention, a fire-resistant coating material is provided on the surface of the wooden member, a joint portion is provided on the fire-resistant coating material at a position corresponding to the recessed portion, and a non-combustible material or an inorganic sealing material and a sealing material having fire-resistant performance are filled and arranged between the joint portion and the steel member, so that the fire-resistant performance of the joint portion can be ensured.

[0068] Further, according to the fire-resistant structure of another wooden-steel joint according to the present invention, a fire-resistant coating material is provided on the surface of the wooden member, a joint portion is provided on the fire-resistant coating material at a position corresponding to the recessed portion, and a fire-resistant paint is provided on the surface of the steel member at a position corresponding to the joint portion, so that the fire-resistant performance of the joint portion can be ensured.

[0069] Further, according to the fire-resistant structure of another wooden-steel joint according to the present invention, the wooden member is a beam member, and the steel member is a steel support, a steel tie or a steel lower chord member arranged on the lower surface side of the wooden member, so that the fire-resistant performance of the joint between the wooden member and the steel support, the steel tie or the steel lower chord member in the cable-stayed beam can be ensured.

Industrial Applicability

[0070] As described above, the fire-resistant structure of the wooden-steel joint according to the present invention is useful for the joint between the wooden member and the steel member, and in particular, is suitable for the joint between the wooden member and the steel member included in the cable-stayed beam or the like.

Explanation of Reference Numerals

[0071] 10 Cable-stayed beam 12 Upper chord beam (wooden member) 14 Tie (steel member) 16 Lower chord member (steel member) 18 Column head 20 Support (steel member) 22, 48, 54 Recessed portion 24 Cement mortar (fire-resistant material) 26 Core material 28 Fire-resistant coating material 30 Steel material 32 Fireproof coating 34 Tip 36, 50, 62 Upper recessed part 38, 52, 64 Lower recessed part 40 Upper part 42 Lower part 44 Non-combustible material 46 Fireproof sealing material 56 Diverging part 58 Plate 60 Stud 66 Steel screw (anti-dropping material) 100, 101, 200, 201, 300, 301 Fireproof structure of wood-steel joint

Claims

1. A fire-resistant structure for a joint between a wooden member and a steel member, comprising a recess provided on the surface of the wooden member, in which a part of the steel member is disposed, and an inorganic fire-resistant material containing moisture, which is filled and disposed in the recess so as to cover the periphery of the steel member in order to reduce heat transfer from the steel member to the wooden member. The fire-resistant structure for a wooden-steel joint is characterized by this.

2. The fire-resistant structure for a wooden-steel joint according to claim 1, further comprising a falling-prevention material for preventing the fire-resistant material from falling off from the recess.

3. A fire-resistant coating material is provided on the surface of the wooden member, a joint portion is provided in the fire-resistant coating material at a position corresponding to the recess, and a non-combustible material or an inorganic sealing material and a sealing material having fire-resistant performance are filled and disposed between the joint portion and the steel member. The fire-resistant structure for a wooden-steel joint according to claim 1 or 2 is characterized by this.

4. A fire-resistant coating material is provided on the surface of the wooden member, a joint portion is provided in the fire-resistant coating material at a position corresponding to the recess, and a fire-resistant paint is provided on the surface of the steel member at a position corresponding to the joint portion. The fire-resistant structure for a wooden-steel joint according to claim 1 or 2 is characterized by this.

5. The wooden member is a beam member, and the steel member is a steel support, a steel bundled member, or a steel lower chord member disposed on the lower surface side of the wooden member. The fire-resistant structure for a wooden-steel joint according to claim 1 or 2 is characterized by this.

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