JP7120702B2 - Steel beam fireproof covering structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a steel beam fireproof covering structure.

A joint structure between a wooden column and a steel beam is known (see Patent Documents 1 and 2, for example).

JP 2014-029093 A JP 2014-029092 A

In the technique disclosed in Patent Literature 1, the steel beams are coated with a fireproof coating so that the heat of fire transferred from the steel beams to the core material of the wooden column does not cause the core material to burn.

However, in the above technique, there is room for further improvement in order to more easily increase the fire resistance of wooden members such as wooden columns.

SUMMARY OF THE INVENTION In view of the above facts, an object of the present invention is to improve the fire resistance of wooden members more easily.

A steel beam fireproof covering structure according to a first aspect includes a wooden member, a pair of flanges that face each other in the vertical direction, and a web that connects the pair of flanges. has a steel beam joined to the wooden member, and a refractory material disposed between the pair of flange portions at the end of the steel beam, and end covering for fireproof coating the end of the steel beam and

According to the steel beam fireproof coating structure according to the first aspect , the steel beam has a pair of flange portions opposed to each other in the vertical direction and a web portion connecting the pair of flange portions. is joined to the wooden member. The ends of the steel beams are refractory coated with end coatings.

The end covering has refractory material disposed between a pair of flanges at the ends of the steel beam. This refractory material reduces fire heat transferred from the ends of the steel beams to the wooden members during a fire. Therefore, the fire resistance of the wooden member is enhanced.

Also, the refractory material is arranged between the pair of flange portions of the steel frame beam as described above. In this case, the refractory material can be easily attached to the steel frame beam, thereby improving the workability of the refractory material.

A steel beam fireproof coating structure according to a second aspect is the steel beam fireproof coating structure according to the first aspect, and includes an intermediate coating portion that coats an intermediate portion of the steel beam in a material axial direction with a fireproof coating. The fire resistance is higher than that of the intermediate coating.

According to the steel frame beam fireproof covering structure according to the second aspect , it is provided with the intermediate covering portion that coats the intermediate portion of the steel frame beam in the material axial direction with fireproof coating. Also, the fire resistance performance of the end covering portion is higher than the fire resistance performance of the intermediate covering portion.

Here, as described above, in the event of a fire, fire heat is transferred from the ends of the steel beams to the wooden members. Therefore, by increasing the fire resistance performance of the end covering part and suppressing the temperature rise at the ends of the steel frame beams, it is possible to efficiently reduce the fire heat transmitted from the ends of the steel frame beams to the wooden members in the event of a fire. can be done.

On the other hand, it is sufficient for the intermediate covering portion to be able to suppress the decrease in rigidity and yield strength of the intermediate portion of the steel frame beam due to the temperature rise at the time of fire. Here, in general, the temperature at which the yield strength and rigidity of the steel frame beams are greatly reduced is higher than the temperature at which the wooden member begins to burn (ignition temperature). Therefore, the fire resistance required for the intermediate covering portion is lower than the fire resistance required for the end covering portion.

Therefore, by making the fire resistance of the intermediate covering portion lower than that of the end covering portion, in other words, by making the fire resistance of the end covering portion higher than that of the intermediate covering portion, It is possible to efficiently suppress the decrease in yield strength and rigidity of steel beams and the burning of wooden members.

A steel beam fireproof covering structure according to a third aspect is the steel beam fireproof covering structure according to the first aspect or the second aspect , wherein the end covering portion is provided at the end portion of the steel beam, and the web portion and the Longitudinal refractory boards are provided facing each other and spanning the pair of flange portions, the refractory material having crystal water or free water and being filled between the web portion and the longitudinal refractory boards.

According to the steel beam fireproof covering structure according to the third aspect , the vertical fireproof board is provided at the end of the steel beam. A vertical fire-resistant board faces the web portion of the steel beam and spans a pair of flange portions. A refractory material is placed between the refractory board and the web portion of the steel beam.

Here, the refractory material has crystal water or free water. When the refractory material is heated, water of crystallization or free water in the refractory material evaporates, thereby suppressing the temperature rise of the refractory material and the ends of the steel beams. Then, the temperature rise of the refractory material and the ends of the steel beams is continuously suppressed until all the crystallization water or free water evaporates.

On the other hand, if the refractory material is directly exposed to flame, the water of crystallization or free water may evaporate instantaneously. In this case, the fireproof performance of the fireproof material is lost early.

In contrast, in the present invention, the refractory material is covered by vertical refractory boards. Since the vertical fireproof board member prevents the fireproof material from being directly exposed to flames in the event of a fire, instantaneous evaporation of water of crystallization or free water in the fireproof material is suppressed. Therefore, the early loss of the fireproof performance of the fireproof material is suppressed.

As described above, according to the steel frame beam fireproof covering structure according to the present invention, the fireproof performance of wooden members can be enhanced more easily.

1 is a side view showing a steel beam and a wooden column to which the steel beam fireproof covering structure according to the first embodiment is applied; FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1; FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1; FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1; FIG. FIG. 2 is a perspective view showing a modification of the steel beam shown in FIG. 1; FIG. 4 is a cross-sectional view corresponding to FIG. 3 showing an axial end portion of a steel beam to which a modification of the steel beam fireproof covering structure according to the first embodiment is applied; FIG. 4 is a cross-sectional view corresponding to FIG. 3 showing an axial end portion of a steel beam to which a modification of the steel beam fireproof covering structure according to the first embodiment is applied; 4A and 4B are cross-sectional views, corresponding to FIG. 3, showing end portions in the material axis direction of a steel beam to which a modification of the steel beam fireproof covering structure according to the first embodiment is applied; FIG. (A) is a cross-sectional view corresponding to FIG. 2 showing an intermediate portion in the material axis direction of a steel beam to which a modified example of the steel beam fireproof covering structure according to the first embodiment is applied; FIG. 4 is a cross-sectional view corresponding to FIG. 3 showing an axial end portion of a steel beam to which a modified example of the steel beam fireproof covering structure according to one embodiment is applied; FIG. 5 is a perspective view showing an axial end portion of a steel beam to which a modification of the steel beam fireproof covering structure according to the first embodiment is applied. FIG. 5 is a cross-sectional view corresponding to FIG. 4 showing an axial end portion of a steel beam to which a modification of the steel beam fireproof covering structure according to the first embodiment is applied; FIG. 5 is a perspective view showing an axial end portion of a steel beam to which a modification of the steel beam fireproof covering structure according to the first embodiment is applied. FIG. 5 is a side view showing a steel beam and a wood beam to which the steel beam fireproof covering structure according to the second embodiment is applied.

(First embodiment)
First, the first embodiment will be described.

(Steel beam)
FIG. 1 shows a steel beam 20 to which the steel beam fireproof covering structure 10 according to the first embodiment is applied. The steel beam 20 is made of H-shaped steel.

As shown in FIGS. 2 and 3 , the steel beam 20 has a pair of flange portions 22 facing each other in the vertical direction and a web portion 24 connecting the pair of flange portions 22 . For example, a reinforced concrete slab 28 is provided on the upper flange portion 22 . An axial end portion 20E (end portion side) of the steel beam 20 is joined to a wooden column 30 (see FIG. 1).

(wooden pillar)
As shown in FIG. 4, the wooden column 30 is formed in a prism shape. A fireproof structure is applied to this wooden column 30 . Specifically, the wooden column 30 has a wooden core 32 that supports a load (vertical load) and a fireproof coating 34 that coats the wooden core 32 with fireproof. Note that the wooden pillar 30 is an example of a wooden member.

(woody core)
The wooden core 32 is made of a wooden material such as laminated wood or solid wood, and has a rectangular cross-section. In addition, the wooden core 32 has rigidity and strength capable of supporting the load (vertical load) borne by the wooden column 30 . The wooden core 32 is covered with a fireproof covering 34 .

(Fire resistant coating)
The fireproof coating 34 has, for example, a burnout layer 36 arranged outside the wooden core 32 and a burnout allowance layer 38 arranged outside the burnout layer 36 . The stop-burn layer 36 stops burning of the burn-off layer 38 in the event of a fire (natural fire extinguishing), and suppresses burning of the woody core 32 . The burn-stop layer 36 is formed in an annular shape along the outer peripheral surface (side surface) of the wooden core portion 32 , surrounds the wooden core portion 32 and covers the outer peripheral surface of the wooden core portion 32 .

The fire stop layer 36 has a plurality of cement-based hardening bodies 36A and wood 36B alternately arranged along the outer peripheral surface of the wooden core 32 . The cement-based hardening body 36A and the wood 36B are formed into prismatic shapes and arranged along the woody core 32 in the axial direction. These cement-based hardening bodies 36A and wood 36B are adhered to the wooden core 32 by, for example, adhesion or the like.

The cement-based hardening body 36A is made of a high-heat-capacity member, such as mortar or grout, which has a higher heat-capacity than the wood 36B. As a result, the heat capacity of the burn-stop layer 36 is larger than the heat capacities of the wooden core 32 and the burn-off layer 38 as a whole. The burn-stop layer 36 stops the burning of the burn-off layer 38 in the event of a fire (natural fire extinguishing), thereby suppressing the burning of the wooden core 32 . A burn allowance layer 38 is arranged outside the burn stop layer 36 .

(burning allowance layer)
The burning margin layer 38 is formed of wood material such as laminated wood, and burns in the event of a fire to form a carbonized layer (heat insulating layer), thereby suppressing the infiltration of fire heat into the wood core portion 32 . The burnout layer 38 is annularly formed along the outer peripheral surface of the burnout layer 36 , surrounds the burnout layer 36 , and covers the outer peripheral surface of the burnout layer 36 . Also, the burnout layer 38 is adhered to the outer peripheral surface of the burnout layer 36 by, for example, an adhesive or the like.

The thickness (layer thickness) of the burn allowance layer 38 is appropriately set according to the fire resistance (fire resistance time) required for the wooden column 30, the burning rate of the burn allowance layer 38, and the heat shielding performance.

A groove portion 40 is formed in the fireproof covering portion 34 to expose the side surface 32S (outer peripheral surface) of the wooden core portion 32 . The groove portion 40 is a rectangular long groove extending in the vertical direction. A bracket 42 is arranged in the groove 40 .

The bracket 42 is formed in a T shape when viewed in plan. This bracket 42 has a base portion 42A and a joint plate portion 42B. The base portion 42</b>A is fixed to the wooden core portion 32 by a plurality of through bolts 44 and nuts 46 penetrating the wooden core portion 32 while being superimposed on the side surface 32</b>S of the wooden core portion 32 .

A groove portion 52 in which the bearing plate 48 and the nut 50 are accommodated is formed on the side surface of the wooden core portion 32 opposite to the groove portion 40 . Moreover, the shape of the bracket 42 is not limited to the T-shape described above, and can be changed as appropriate.

The joint plate portion 42B extends from the base portion 42A toward the steel beam 20 side. The joint plate portion 42B is joined to the web portion 24 by bolts 54 and nuts 56 while being superimposed on the web portion 24 of the steel beam 20 .

A through hole 26 (see FIG. 5) for a bolt 54 is formed in the web portion 24 of the end portion 20E of the steel frame beam 20. As shown in FIG. Also, the joining plate portion 42B may be joined to the web portion 24 not only by the bolts 54 and the nuts 56, but also by welding or the like. A heat insulating material 58 such as rock wool is provided in the groove 40 to close the gap between the groove 40 and the end 20E of the steel frame beam 20 .

(Steel beam fireproof covering structure)
As shown in FIG. 1 , the steel beam fireproof covering structure 10 has an intermediate covering portion 60 and end covering portions 70 . The intermediate covering portion 60 covers the axially intermediate portion 20M of the steel beam 20 with a fireproof coating. On the other hand, the end covering portion 70 covers the axial end portion 20E of the steel beam 20 with a fireproof coating.

Here, in the event of a fire, fire heat is transferred from the ends 20E of the steel beams 20 to the wooden columns 30 . Therefore, when the temperature of the end portion 20E of the steel beam 20 rises in the event of a fire, not only is the strength and rigidity of the end portion 20E reduced, but the wood column 30 may also burn. On the other hand, the intermediate portion 20M of the steel frame beam 20 may be provided so long as the yield strength and rigidity are not lowered in the event of a fire.

Here, generally, the temperature at which the strength and rigidity of the steel beam 20 begin to significantly decrease (eg, 350° C. to 500° C.) is higher than the temperature at which the wooden column 30 begins to burn (ignition temperature, eg, 260° C.). Therefore, if the entire length of the steel beam 20 is uniformly covered with a fireproof coating so that the bearing strength and rigidity of the steel beam 20 do not decrease, the fire heat transmitted from the end 20E of the steel beam 20 to the wooden column 30 will cause the wooden column 30 to be damaged. may burn.

As a countermeasure, in the present embodiment, the fire resistance of the end covering portion 70 is made higher than the fire resistance of the intermediate covering portion 60, thereby suppressing combustion of the wooden column 30 in the event of a fire. The configurations of the intermediate covering portion 60 and the end covering portion 70 will be specifically described below.

(Intermediate coating)
As shown in FIG. 2 , the intermediate coating portion 60 coats the axial intermediate portion 20M of the steel beam 20 according to the fire resistance (fire resistance time) required for the steel beam 20 . That is, the intermediate coating portion 60 coats the intermediate portion 20M of the steel frame beam 20 in the material axial direction so that the yield strength and rigidity of the steel frame beam 20 are not reduced in the event of a fire.

The intermediate covering portion 60 is made of, for example, sprayed rock wool. The intermediate covering portion 60 covers the outer surfaces of the web portion 24 of the steel beam 20 and the lower flange portion 22, and also covers the outer surfaces of the upper flange portion 22 other than the upper surface 22U.

The fire resistance of the intermediate covering portion 60 is appropriately set according to the fire resistance required for the steel beam 20 . In other words, the fire resistance performance of the intermediate covering portion 60 is appropriately set so that the steel beam 20 does not reach a predetermined temperature in the event of a fire.

Note that the intermediate portion 20M of the steel beam 20 in the material axial direction means a portion between the ends 20E on both sides of the steel beam 20 in the material axial direction. Further, the end portion 20E of the steel beam 20 in the material axial direction means a region including at least the entire joint plate portion 42B of the bracket 42 from the end surface 20T of the steel beam 20 .

(End cover)
The end covering 70 prevents the wood pillar 30 (wood core 32) from burning due to the heat transferred from the end 20E of the steel beam 20 to the wood pillar 30 in the event of a fire. 32), the end 20E of the steel beam 20 is coated with a fireproof coating so that it does not reach the ignition temperature.

The end covering 70 includes partition boards 72 , vertical refractory boards 74 and filler concrete 78 . The partition board 72 and the vertical fireproof board 74 are formed in a rectangular plate shape by, for example, a calcium silicate board with high heat insulation.

The partition board 72 is arranged along the boundary between the intermediate portion 20M and the end portion 20E of the steel beam 20. As shown in FIG. Also, the partition board 72 is arranged closer to the center of the steel beam 20 (on the side opposite to the wooden column 30) than the joint plate portion 42B of the bracket 42 is.

The partition boards 72 are arranged on both sides of the web portion 24 of the steel beam 20 respectively. Each partition board 72 is arranged between the pair of flange portions 22 . Each partition board 72 faces the wooden column 30 and is arranged across the pair of flange portions 22. At least one of the pair of flange portions 22 and the web portion 24 is attached to the pair of flange portions 22 and the web portion 24 by an adhesive, a screw, or the like (not shown). Fixed. The partition board 72 partitions the space between the pair of flange portions 22 in the axial direction of the steel beam 20 .

Note that the partition board 72 is not limited to a fireproof board, and may be formed of, for example, a metal plate.

As shown in FIG. 3 , the vertical fireproof board 74 fills the space (hereinafter referred to as “filling space”) between the pair of flanges 22 together with the partition board 72 at the end 20E of the steel beam 20 on the wooden column 30 side. are partitioned. Specifically, the vertical fireproof boards 74 are arranged on both sides of the web portion 24 respectively. Each vertical refractory board 74 is arranged between a pair of flange portions 22 . In addition, the vertical fireproof board 74 is an example of a form board.

Each vertical fireproof board 74 faces the web portion 24 of the steel beam 20 and is arranged across the pair of flange portions 22. The pair of flange portions 22 and the web portion 24 are connected by adhesive, screws, or the like (not shown). fixed on at least one side. Furthermore, the vertical fireproof board 74 is arranged over the partition board 72 and the end surface 20T (see FIG. 4) of the steel frame beam 20 on the wooden column 30 side. A filling space 76 between the pair of flange portions 22 is defined by the vertical fireproof board 74 and the partition board 72 . This filling space 76 is filled with filling concrete 78 .

The filling concrete 78 is, for example, cast-in-place concrete. The filling concrete 78 fills the filling space 76 through a filling hole 80 formed in the upper flange portion 22 of the steel beam 20 . Note that the filled concrete 78 is an example of a refractory material and a filled refractory material.

Fill concrete 78 has free water. The outer surface 78S of the filling concrete 78 is covered with a vertical fireproof board 74 for fireproofing. Also, the joint plate portion 42B of the bracket 42, the bolt 54, and the nut 56 are embedded in the filling concrete 78. As shown in FIG. Due to the filling concrete 78 and the vertical fireproof boards 74 , the fire resistance (fire resistance time) of the end covering portion 70 is higher than the fire resistance performance (fire resistance time) of the intermediate covering portion 60 .

Note that, as shown in FIG. 5 , notch portions 82 may be formed in the flange portions 22 of the steel beams 20 instead of the filling holes 80 . In addition, when the cross-sectional loss of the flange portion 22 due to the filling hole 80 or the notch portion 82 becomes a problem, the filling hole is formed in the vertical fireproof board 74 or the like instead of forming the filling hole 80 in the flange portion 22. Also good.

Also, the end covering portion 70 and the intermediate covering portion 60 may be partially overlapped. As a result, opening of the boundary (boundary joint) between the end covering portion 70 and the intermediate covering portion 60 in the event of a fire is suppressed.

(Action)
Next, the operation of the first embodiment will be described.

According to this embodiment, the steel beam fireproof coating structure 10 has end coating portions 70 and intermediate coating portions 60 . The end covering portion 70 covers the end portion 20E of the steel beam 20 on the side of the wooden column 30 with a fireproof coating. As a result, the temperature rise of the ends 20E of the steel beams 20 during a fire is suppressed, and fire heat transferred from the ends 20E to the wooden columns 30 is reduced. Therefore, the fire resistance of the wooden pillar 30 can be enhanced.

In addition, the fireproof performance of the end covering portion 70 is higher than the fireproof performance of the intermediate covering portion 60 that coats the intermediate portion 20M of the steel beam 20 with fireproofing. Here, as described above, the intermediate covering portion 60 only needs to be capable of suppressing a decrease in yield strength and a decrease in rigidity of the intermediate portion 20M of the steel beam 20 due to an increase in temperature during a fire. In general, the temperature at which the stiffness of the steel beam 20 begins to decrease (eg, 350° C. to 500° C.) is higher than the temperature at which the wooden column 30 begins to burn (ignition temperature, eg, 260° C.). Therefore, the fire resistance required for the intermediate covering portion 60 is lower than the fire resistance required for the end covering portion 70 .

Therefore, by making the fire resistance of the intermediate covering portion 60 lower than the fire resistance of the end covering portion 70, in other words, by making the fire resistance of the end covering portion 70 higher than the fire resistance of the intermediate covering portion 60, , it is possible to efficiently suppress the decrease in strength and rigidity of the steel beams 20 and the burning of the wooden columns 30 in the event of a fire.

The end covering 70 also has a filling concrete 78 that fills a filling space 76 between the pair of flanges 22 . Fill concrete 78 has free water. This free water evaporates in the event of a fire, thereby suppressing the temperature rise of the filling concrete 78 and the ends 20E of the steel beams 20 . In addition, the temperature rise of the filling concrete 78 and the ends 20E of the steel beams 20 is continuously suppressed until all the free water in the filling concrete 78 evaporates. Therefore, the fire resistance performance of the ends 20E of the steel beams 20 can be efficiently improved.

Furthermore, in this embodiment, by filling the filling space 76 with the filling concrete 78, the heat capacity of the end portion 20E of the steel beam 20 is dramatically increased. Therefore, the fireproof coating on the lower surface of the flange portion 22 on the lower side of the steel beam 20 can be omitted. Therefore, the effective space below the ends 20E of the steel beams 20 can be expanded.

Here, if the filling concrete 78 is directly exposed to a flame, the free water in the filling concrete 78 can instantly evaporate. In this case, the fire resistance performance of the filled concrete 78 may be lost prematurely.

On the other hand, the filling concrete 78 of this embodiment fills the filling space 76 between the pair of flange portions 22 partitioned by the partition board 72 and the vertical fireproof board 74 . That is, the outer surface 78S of the filling concrete 78 is covered with the vertical fireproof board 74 for fireproofing. Since the vertical fireproof board 74 prevents the filling concrete 78 from being directly exposed to flames in the event of a fire, free water in the filling concrete 78 is suppressed from instantaneously evaporating. Therefore, early loss of the fire resistance performance of the filling concrete 78 is suppressed.

Furthermore, the vertical fireproof board 74 of this embodiment is formed of a calcium silicate board or the like with high heat insulation. This further suppresses the instantaneous evaporation of free water in the filling concrete 78 .

Further, the filling concrete 78 is filled in the filling space 76 as described above. Thereby, when constructing the filling concrete 78, the pair of flange portions 22 of the steel beam 20, the partition board 72, and the vertical fireproof board 74 function as formwork. Therefore, the workability of the filling concrete 78 is improved.

(Modification of first embodiment)
Next, a modified example of the first embodiment will be described.

In the modification shown in FIG. 6, the filling space 76 is defined by a metal plate 92 instead of the vertical fireproof board 74 according to the first embodiment. Note that the metal plate 92 is an example of a formwork plate.

Specifically, the metal plate 92 of the end covering portion 90 is formed in a rectangular plate shape by using a steel plate or the like, for example. The metal plate 92 faces the web portion 24 of the steel beam 20 and is arranged across the pair of flange portions 22 . Also, the metal plate 92 is joined to the ends of the pair of flange portions 22 by welding or the like. A filling concrete 78 is filled in the filling space 76 defined by the metal plate 92 and the partition board 72 (see FIG. 1).

By partitioning the filling space 76 with the metal plate 92 in this manner, attachment of the metal plate 92 to the steel frame beam 20 and the like are facilitated.

Also, the outer surface of the metal plate 92 is coated with a fireproof coating material 94 for fireproofing. The fireproof covering material 94 is, for example, sprayed rock wool or the like. The refractory coating material 94 suppresses the temperature rise of the metal plate 92 in case of fire.

The fire-resistant coating material 94 is not limited to the sprayed rock wool, and may be, for example, a sheet-like wound fire-resistant material made of rock wool or the like, or a fire-resistant paint. Moreover, when a fire-resistant paint is used, the surface (metal surface) of the metal plate 92 can be utilized for the design.

Also, the temperature rise of the metal plate 92 in the event of fire is suppressed by the filling concrete 78 . Therefore, the fireproof coating material 94 may be provided on the metal plate 92 as required, and can be omitted as appropriate.

Next, in the modification shown in FIG. 7, the outer shape of the end covering portion 100 is the same as the outer shape of the intermediate covering portion 60 (see FIG. 2). Specifically, the metal plate 102 of the end covering portion 100 is formed with a concave portion 104 that is concave toward the web portion 24 side of the steel beam 20 so as to match the outer shape of the intermediate covering portion 60 . By matching the external shapes of the end covering portion 100 and the intermediate covering portion 60 in this way, the design is improved.

It should be noted that, as in the modification shown in FIG. 8A, it is also possible to dispose a flat metal plate 106 inside the end portions of the pair of flange portions 22 .

Next, in the above embodiment, the filling concrete 78 was provided between the pair of flanges 22 of the steel beam 20, but as shown in FIG. You may provide the fireproof board 108 as.

The fireproof board 108 is made of, for example, a calcium silicate board, a gypsum board, or the like, and is arranged in a laminated state between the pair of flange portions 22 . This fireproof board 108 can also reduce fire heat transferred from the ends 20E of the steel beams 20 to the wooden columns 30 .

Also, by providing the fireproof board 108 between the pair of flange portions 22 of the steel beam 20 , the fireproof board 108 can be easily attached to the steel beam 20 . Therefore, the workability of the fireproof board 108 is improved.

In addition, it is also possible to provide a sheet-like wrapping fire-resistant material made of rock wool or the like between the pair of flange portions 22 .

Next, in the modification shown in FIGS. 9A and 9B, the intermediate covering portion 110 and the end covering portion 112 each have a vertical fireproof board 114 and a horizontal fireproof board 116 surrounding the steel beam 20. is doing. As a result, the intermediate covering portion 110 and the end covering portion 112 have the same outer shape (cross-sectional shape).

The vertical fireproof board 114 and the horizontal fireproof board 116 are made of calcium silicate board or the like. The vertical fireproof boards 114 are arranged on both sides of the pair of flange portions 22 in the width direction. Each vertical fireproof board 114 faces the web portion 24 and extends across the pair of flange portions 22 .

The horizontal fireproof board 116 is arranged along the lower surface of the lower flange portion 22 and covers the lower surface with a fireproof coating. Also, the horizontal fireproof boards 116 are arranged over the vertical fireproof boards 114 . The horizontal fireproof board 116 and the vertical fireproof board 114 have a U-shaped cross section with an open upper side, and cover the outer surfaces (side surfaces and lower surface) of the steel beam 20 other than the upper surface with fireproof coating.

Here, as shown in FIG. 9B, the end covering 112 has a filling concrete 78 . The filling concrete 78 is filled in the filling space 76 defined by the vertical fireproof boards 114 and the horizontal fireproof boards 116 . As a result, the fire resistance of the end covering portion 112 is higher than that of the intermediate covering portion 110 .

By using the vertical fire-resistant boards 114 and the horizontal fire-resistant boards 116 in this way, the external shapes of the intermediate covering portion 110 and the end covering portion 112 can be easily matched.

Next, in the modification shown in FIGS. 10 and 11, an end plate 120 is provided on the end surface 20T of the steel beam 20. As shown in FIG. The end plate 120 is joined to the end surface 20T of the steel beam 20 by welding or the like. A plurality of through holes 122 are also formed in the end plate 120 .

As shown in FIG. 11 , the end plate 120 is fixed to the wooden core 32 by means of through-bolts 44 and nuts 46 while overlapping the side surface 32S of the wooden core 32 . In this way, instead of the bracket 42 (see FIG. 4), it is also possible to join the wooden column 30 and the end portion 20E of the steel beam 20 via the end plate 120. FIG.

As shown in FIG. 12, cap nuts 128 to which the through-bolts 44 are fastened may be previously fixed to the end plate 120 by welding or the like.

(Second embodiment)
Next, a second embodiment will be described. In addition, in the second embodiment, members having the same configuration as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In the second embodiment, as shown in FIG. 13, the ends 20E of the steel beams (small steel beams) 20 are joined to the wooden beams 130 .

Specifically, the wooden beam 130 has a wooden core 132 that supports a load (vertical load) and a fireproof coating 134 that coats the wooden core 132 with fireproof. Note that the wooden beam 130 is an example of a wooden member.

The configurations of the wooden core 132 and the fireproof covering 134 of the wooden beam 130 are basically the same as those of the wooden core 32 and the fireproof covering 34 of the wooden column 30 according to the first embodiment, except that the wooden beam 130 has the same structure as the wooden core 32 and the fireproof covering 34 of the wooden beam. At 130 a slab 28 is provided on top of the wood core 132 . Therefore, the outer peripheral surface (side surface and lower surface) of the wooden beam 130 other than the upper surface is covered with a fireproof covering portion 134 .

Here, the end portion 20E of the steel beam 20 is joined to the wooden core portion 132 of the wooden beam 130 via the bracket 42 . End portions 20E of the steel beams 20 are provided with end covering portions 70, as in the first embodiment.

As a result, the end covering portion 70 suppresses the temperature rise of the end portion 20E of the steel beam 20 in the event of a fire, and prevents the fire from being transmitted from the end portion 20E of the steel beam 20 to the wooden core portion 132 of the wooden beam 130. Heat is reduced. Therefore, effects similar to those of the first embodiment can be obtained.

The ends 20E of the steel beams 20 may be joined to the wooden beams 130 not only through the brackets 42 but also through the aforementioned end plates 120 (see FIG. 11) or the like.

(Modification)
Next, modified examples of the first embodiment and the second embodiment will be described. Various modifications will be described below using the first embodiment as an example, but these modifications can also be applied to the second embodiment.

In the above-described first embodiment, the refractory material is the filled concrete 78, but the refractory material may be, for example, cement-based fillers (filled refractory materials) such as concrete, grout, and mortar. The refractory material may be gypsum, aluminum hydroxide, or the like containing water of crystallization, or rockl, or the like, containing free water. In addition, in the refractory material containing water of crystallization, the temperature rise of the refractory material is suppressed by evaporating the water of crystallization at the time of fire.

In addition, in the first embodiment, the vertical fire-resistant board 74 is made of calcium silicate board, and the vertical fire-resistant board is, for example, a gypsum board, a rock wool board, a mortar board, a ceramic fiber board, a PC board, or an ALC. It may be a board or the like.

In addition, in the above-described first embodiment, the intermediate covering portion 60 is formed of sprayed rock wool. It may be made of material or fire-resistant paint. Moreover, the intermediate covering portion 60 may be provided according to the fire resistance required for the steel beam 20, and may be omitted as appropriate.

Further, the flame stop layer 36 of the wooden column 30 in the first embodiment may be a layer capable of suppressing the penetration of flame heat into the wooden core 32. For example, a flame-retardant layer ( It may be a flame-retardant layer) or an endothermic layer capable of absorbing heat (endothermic type).

Examples of the flame-retardant layer include a flame-retardant agent-infused layer obtained by injecting a flame-retardant agent into wood to make it non-combustible. The heat absorbing layer may be formed of a material having a higher heat capacity than general wood, a material having higher heat insulation than general wood, or a material having higher thermal inertia than general wood. It may be formed by appropriately combining with wood. Furthermore, flame-retardant layers and heat-absorbing layers may be appropriately combined (for example, flame-retardant layers and heat-absorbing layers may be alternately arranged) to form a flame-stopping layer or the like.

Examples of materials having a larger heat capacity than general wood include mortar, stone, glass, fiber-reinforced cement, inorganic materials such as gypsum, and various metal materials. In addition, calcium silicate boards, rock wool, glass wool, etc., can be cited as materials having higher heat insulating properties than general wood. Examples of materials having higher thermal inertia than general wood include wood such as ceranganbatsu, jara, and bongoshi.

In addition, in the first embodiment, an example in which the fireproof coating 34 has a two-layer structure of the burn-stop layer 36 and the burn-off layer 38 is shown, but the present invention is not limited to this. For example, the fire stop layer 36 may be omitted and the fire resistant coating 34 may be composed only of the fire stop layer 38, or the fire stop layer 38 may be omitted and the fire resistant coating 34 may be configured only of the fire stop layer 36. Also good. Also, the wooden column may be of a non-fireproof structure without a fireproof coating.

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment and various modifications may be used in combination as appropriate. It goes without saying that various aspects can be implemented without departing from the scope.

10 steel beam fireproof covering structure 20 steel beam 20E end (end of steel beam in material axial direction)
20M Intermediate part in the axial direction of the intermediate steel beam)
22 flange portion 24 web portion 30 wooden column (wooden member)
60 Intermediate covering portion 70 End covering portion 74 Vertical fireproof board 78 Filled concrete (refractory material)
100 End Covering Part 110 Intermediate Covering Part 112 End Covering Part 114 Vertical Fireproof Board 130 Wood Beam (Wood Member)

Claims (4)

a wooden member;
a steel frame beam having a pair of flanges opposed to each other in the vertical direction and a web portion connecting the pair of flanges, and having axial ends joined to the wooden member;
a formwork plate provided at the end of the steel beam and facing the web portion and extending over the pair of flange portions; and a cement-based filler filled between the web portion and the formwork plate. and an end covering portion that coats the end portion of the steel beam with a fireproof coating so that the fireproof performance of the end portion is higher than the fireproof performance of an intermediate portion of the steel beam in the material axial direction ;
Steel beam fireproof cladding structure with The formwork plate is a vertical fireproof board or a metal plate,
The steel beam fireproof covering structure according to claim 1. a wooden member;
a steel frame beam having a pair of flanges opposed to each other in the vertical direction and a web portion connecting the pair of flanges, and having axial ends joined to the wooden member;
A fireproof board is disposed between the pair of flanges at the end of the steel beam, the end of the steel beam is covered with a fireproof coating, and the fireproof performance of the end is measured in the axial direction of the steel beam. and an end covering portion that enhances the fire resistance performance of the middle portion of the
Steel beam fireproof cladding structure with An intermediate coating portion for fireproof coating the intermediate portion of the steel beam,
Fire resistance of the end covering is higher than fire resistance of the intermediate covering,
The steel beam fireproof covering structure according to any one of claims 1 to 3.

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