JP5314356B2 - Composite beam, composite beam construction method, and fireproof building - Google Patents

Description

  The present invention relates to a composite beam, a composite beam construction method, and a fireproof building.

  The floor height of the building is a living space for living and a space other than the living space where the beams, concrete slabs, etc. constituting the building are arranged (hereinafter referred to as “ceiling space” as representative of these spaces). Is the total height.

  In recent years, for the purpose of improving the living performance, there is a demand to increase the ceiling height of the living space even at the same floor height. In addition, there is a demand to reduce the floor height and increase the number of floors without sacrificing the living space for the purpose of securing an effective area of the building as much as possible. Both requests can be resolved by lowering the height of the ceiling.

  However, the height of the ceiling base is a large proportion of the total thickness of the concrete slab and the height of the beam that supports the concrete slab placed on the upper surface (beam formation). The thickness and beam formation of concrete slabs are factors that directly affect the strength of the building and need to be lowered without degrading the performance of the building.

  Conventionally, when the ceiling area is unavoidably lowered, it is out of the design of an appropriate H-section steel, but the beam section is lowered by using a H-section steel with a low cross-section, and the ceiling section is lowered accordingly. It corresponded by the method to do. However, the use of H-section steel with a flat cross-section is not preferable because it involves an increase in the weight of the steel frame and an increase in price, and there is a need for a technique that uses H-section steel with an appropriate cross-section to lower the ceiling. .

  Furthermore, a building having a living space is required to be a fireproof building. In a fireproof building, it is necessary to apply a fireproof coating to the portion of the steel beam (H-shaped steel) exposed in the space, and the thickness of the fireproof coating is also added to the height of the ceiling. For this reason, in order to lower the ceiling space, it is necessary to have a configuration that satisfies the fire resistance performance without using a fireproof coating material.

  As a technology to meet the desire to lower the ceiling space, the upper surface of the upper flange of the H-section steel and the upper surface of the concrete slab are aligned, and the upper portion of the H-section steel is embedded in the concrete slab so that the thickness of the concrete slab is the ceiling. A structure that lowers the position has been proposed (Patent Document 1).

  However, as shown in FIGS. 9A and 9B, Patent Document 1 supports a concrete slab 2 with a slab receiving jig 4 attached to a web 1 c of an H-section steel 1. For this reason, the addition of the slab receiving jig 4 and the operation | work which attaches the slab receiving jig 4 to the web 1c are needed separately.

  Furthermore, as shown in FIGS. 9C and 9D, when Patent Document 1 is applied to a fireproof building, the exposed portion of the H-section steel 1 must be covered with a fireproof coating material 7. That is, it is necessary to cover the surfaces of the web 1c, the slab receiving jig 4, and the lower flange 1b exposed below the concrete slab 2 with the fireproof coating material 7.

As a result, the lower surface of the lower flange 1 b is also covered with the fireproof coating material 7, so that the height of the ceiling is increased by the thickness of the fireproof coating material 7.
JP 2002-188209 A

  In view of the above-described facts, the present invention has an object of using a H-section steel having an appropriate cross-sectional shape and satisfying fire resistance to lower the ceiling space.

The composite beam according to the first aspect of the present invention is attached to the stud, an H-shaped steel, a stud joined to the lower surface of the upper flange of the H-shaped steel, and both surfaces of the web of the H-shaped steel. Reinforcing bars and concrete are cast on both sides of the web from the upper surface of the lower flange of the H-shaped steel to the bottom of the stud joined to the lower surface of the upper flange, and are joined to both sides of the web stud and the reinforcement is embedded within, the precast webs concrete is cured, the beam member having a, on the upper surface of the precast webs concrete, so that the stud is joined to a lower surface of said upper flange is embedded concrete and Da設and characterized by having a, a concrete slab which is flush with the upper surface and the slab surface of the upper flange of the H-shaped steel That.

According to the invention described in claim 1 , the composite beam has a beam member and a concrete slab, and the beam member is provided on both sides of the H-shaped steel, the lower surface of the upper flange of the H-shaped steel, and the web of the H-shaped steel. Concrete is cast on both sides of the web from the upper surface of the lower flange of the H-section steel to the lower surface of the upper flange, And a precast web concrete cured with a stiffener and a reinforcing bar embedded inside. The concrete slab is made by placing concrete so that the stud joined to the lower surface of the upper flange is embedded in the upper surface of the precast web concrete so that the upper surface of the upper flange of the H-section steel and the slab surface are flush with each other. ing.
As a result, the ceiling space can be reduced by the thickness of the concrete slab. At this time, an H-section steel having an appropriate cross-sectional shape is used, and there is no decrease in strength as the H-section steel.
Moreover, since the upper flange and the lower flange of the H-section steel are thermally separated by the concrete slab, the upper flange and the lower flange are not heated at the same time in the event of a fire, and the heat resistance performance of the H-section steel is improved. . Further, the heat capacity of the web concrete constructed on both sides of the H-shaped steel web suppresses the temperature rise of the web.

Also, by pre-fixing the precast web concrete on both sides of the H-shaped steel web in advance, it is possible to eliminate the concrete placement work on site and shorten the construction period.
Furthermore, in addition to the improvement in fire resistance performance by slab concrete, the temperature rise of the H-shaped steel web is also suppressed by the heat capacity of precast web concrete.

By setting it as the above-mentioned structure, the fireproof standard requested | required of H-section steel can be satisfied, and even when applied to a fireproof building, the fireproof coating of the lower surface of a lower flange becomes unnecessary. As a result, the ceiling space can be reduced by the thickness of the fireproof coating material.
Furthermore, the mass of H-section steel increases with web concrete, and the transverse vibration of H-section steel can be suppressed. As a result, it is possible to reduce the number of small beams used to suppress the lateral vibration of the H-shaped steel.

According to a second aspect of the present invention, there is provided a method for constructing a composite beam , comprising joining a stud to the lower surface of an upper flange of an H-shaped steel and both surfaces of the web of the H-shaped steel, attaching reinforcing bars to the stud, Concrete from the upper surface of the lower flange of the steel to the bottom of the stud bonded to the lower surface of the upper flange so that the studs and the reinforcing bars bonded to both sides of the web are embedded inside both sides of the web. A precast web concrete to form a beam member, a step of bridging the beam member between columns, and an upper surface of the precast web concrete and a lower surface of the upper flange Concrete is laid so that the studs embedded are embedded, and the upper surface of the upper flange of the H-shaped steel and the slab surface are flush with each other. And a step of forming a toslab .

According to the second aspect of the invention, first, in the step of forming the beam member, the stud is joined to the lower surface of the upper flange of the H-shaped steel and the both surfaces of the web of the H-shaped steel, and the reinforcing bars are attached to the stud. From the upper surface of the lower flange of the H-shaped steel to the bottom of the stud bonded to the lower surface of the upper flange, concrete is placed on both sides of the web so that the studs and reinforcing bars bonded to both sides of the web are embedded inside And cured to form precast web concrete.
Next, the beam member is bridged between the columns in the step of bridging the beam member. Next, in the step of forming the concrete slab, the stud joined to the lower surface of the upper flange is embedded in the upper surface of the precast web concrete so that the upper surface of the upper flange of the H-shaped steel and the slab surface are flush with each other. Place concrete in the wall.

  Thus, in the construction of the concrete slab, the workability is improved because the slab is supported on the upper surface of the precast web concrete. Further, the web does not require a slab bracket.

A fire-resistant building according to the invention of claim 3 is characterized in that the composite beam according to claim 1 or the composite beam constructed by the composite beam construction method according to claim 2 is connected to a column. Yes.
Thereby, also in a fireproof building, the fireproof coating | covering material of the lower surface of the lower flange of H-shaped steel becomes unnecessary, and a ceiling place can be made low.

  Since this invention is set as the said structure, it can use the H-section steel of a suitable cross-sectional shape, and can satisfy fireproof performance, and can make a ceiling space low.

(First embodiment)
As shown in FIG. 1, the composite beam 10 according to the first embodiment has an H-shaped steel 12.
Studs 24 are joined to the lower surface of the upper flange 14 of the H-shaped steel 12 and both surfaces of the web 18, and reinforcing bars 26 are attached to the studs 24. The composition of the H-shaped steel 12 is H, and is spanned between columns not shown. On both surfaces of the web 18, web concrete 22 is placed between the upper surface of the lower flange 16 and the lower surface of the concrete slab 20 with the width of the lower flange 16.

  The web concrete 22 is placed together with the concrete slab 20 and supports the concrete slab 20. The web concrete 22 is prevented from falling by a stud 24 joined to both surfaces of the web 18 and a reinforcing bar 26 attached to the tip of the stud 24.

  The concrete slab 20 has a thickness h, and a main reinforcement 28 and a reinforcement bar 30 are arranged inside. The upper surface of the concrete slab 20 has the same height as the upper surface of the upper flange 14 of the H-section steel 12, and the upper flange 14 of the H-section steel 12 and the upper portion of the web 18 are embedded in the concrete slab 20.

  By setting it as the above-mentioned structure, even if it is not set as the height which added the thickness h of the concrete slab 20 to the component H of the H-section steel 12, the concrete slab 20 can be supported by the H-section steel 12.

  That is, as shown in FIG. 2A, conventionally, when the concrete slab 20 is supported by the H-section steel 12, the concrete slab 20 is placed on the upper surface of the upper flange 14 of the H-section steel 12. For this reason, it is necessary to ensure the height (H + h), which is the sum of the height H of the H-section steel 12 and the thickness h of the concrete slab 20. Since there is no other means to reduce the height (H + h), the performance of the H-section steel 12 is reduced. However, the H-section steel of the H-section steel 12 is reduced by using the H-section steel having a flat cross section. It was supported by the method.

  On the other hand, as shown in FIG. 2 (B), the composite beam 10 has the upper surface of the concrete slab 20 and the upper surface of the upper flange 14 of the H-section steel 12 flush with each other. By embedding the portion, the total height of the concrete slab 20 and the H-section steel 12 that supports the cleat slab 20 can be suppressed to the formation H of the H-section steel 12.

At this time, the H-section steel 12 can have an appropriate cross-sectional shape, and the performance of the H-section steel 12 does not deteriorate.
Next, the fire resistance performance of the composite beam 10 will be described.

  As shown in FIG. 2 (A), in the fireproof building, the exposed portion of the H-section steel 12 needs to be covered with a fireproof covering material 38 having a thickness s in order to satisfy the fireproof performance.

  However, with the configuration of the composite beam 10 shown in FIG. 2B, the concrete slab 20 acts as a heat insulator when a fire occurs on either the upper floor or the lower floor of the concrete slab 20. The upper flange 14 and the lower flange 16 of the H-shaped steel 12 are thermally divided. Thereby, the upper flange 14 and the lower flange 16 can be prevented from being heated simultaneously, and the heat resistance performance of the H-section steel 12 is improved.

  Furthermore, the web concrete 22 constructed on both sides of the web 18 also acts as a thermal insulator, preventing the web 18 from being directly exposed to the flame. At the same time, the temperature increase of the web 18 is suppressed by the heat capacity of the web concrete 22.

  Thus, by embedding the H-section steel 12 in the concrete slab 20 and the web concrete 22, the fire resistance standard required for the H-section steel 12 can be satisfied. As a result, when the composite beam 10 is applied to a fireproof building, the fireproof covering material (thickness s) becomes unnecessary even though the lower surface of the lower flange 16 is exposed.

  In this way, the composite beam 10 has a total height of the concrete slab 20 and the H-shaped steel 12 supporting the cleat slab 20 as compared with the conventional structure, and the thickness h of the concrete slab 20 and the thickness s of the fireproof coating material. The total dimension can be lowered. That is, the ceiling area (not shown) can be lowered.

  Next, the construction method of the composite beam 10 will be described.

  As shown in FIG. 3, first, the studs 24 are joined to the lower surface of the upper flange of the H-shaped steel 12 and both surfaces of the web 18, and the reinforcing bars 26 for preventing the fall are attached to the studs 24. Next, the H-section steel 12 is spanned between columns (not shown), and a slab formwork 32 is laid down from the upper surface of the upper flange 14 of the H-section steel 12 by a thickness h of the concrete slab 20, and the main bars 28 are arranged. The reinforcement 30 is arranged.

  Next, the web formwork 34 is attached to both sides of the web 18 of the H-section steel 12. At this time, the web formwork 34 is arranged in the vertical direction in the range from the tip of the lower flange 16 of the H-shaped steel 12 to the lower surface of the slab formwork 32.

  Thereafter, concrete 36 is placed on the slab formwork 32. At this time, the concrete 36 is also placed between the web formwork 34 and the web 18 together. As a result, the concrete slab 20 and the web concrete 22 can be constructed as a single unit with the stud 24 and the reinforcing bar 26 embedded therein.

  After curing, since the web concrete 22 supports the concrete slab 20, it is not necessary to fix a slab support for supporting the concrete slab 20 to the web 18.

  Furthermore, the mass of the H-section steel 12 increases in the web concrete 22. As a result, it is possible to suppress the H-shaped steel 12 from vibrating in the lateral direction due to minute vibrations propagated from the surroundings, and to reduce the number of small beams used to suppress the horizontal vibration of the H-shaped steel 12.

(Second Embodiment)
As shown in FIG. 4, the composite beam 40 according to the second embodiment has an H-section steel 42 that is an H-section steel. A stud 24 is joined to the lower surface of the upper flange 44 of the H-shaped steel 42 and both surfaces of the web 48, and a reinforcing bar 26 is attached to the stud 24.
The H-shaped steel 42 is formed as H and is spanned between pillars (not shown). On both surfaces of the web 48, a precast web concrete 50 is fixed between the upper surface of the lower flange 16 and the lower surface of the concrete slab 20 with the width of the lower flange 16.

  The precast web concrete 50 is fixed before the H-shaped steel 42 is bridged, and supports the concrete slab 52. The precast web concrete 22 is prevented from falling by a stud 24 joined to both surfaces of the web 18 and a reinforcing bar 26 attached to the tip of the stud 24.

  The concrete slab 52 has a thickness h, and a main reinforcement 54 and a distribution reinforcement 56 are arranged inside. The upper surface of the concrete slab 52 has the same height as the upper surface of the upper flange 44 of the H-section steel 12, and the lower surface is supported by the precast web concrete 50. The upper flange 44 of the H-shaped steel 42 and the upper part of the web 48 are embedded in the concrete slab 52.

  By adopting the above-described configuration, the concrete slab 52 can be supported by the H-shaped steel 42 even if the height H of the concrete slab 52 is not added to the height H of the H-shaped steel 42.

  That is, as described in the first embodiment, the concrete slab 52 can be supported by the H-section steel 42 without using the configuration shown in FIG. 5 (A), and the concrete slab as shown in FIG. 5 (B). The upper surface of 52 and the upper surface of the upper flange 14 of the H-shaped steel 42 are flush with each other, and a part of the H-shaped steel 42 is embedded in the concrete slab 52, thereby supporting the concrete slab 52 and the cleat slab 52. The total height of the steels 42 can be made the composition H of the H-section steel 42.

At this time, the H-section steel 42 can have an appropriate cross-sectional shape, and the performance of the H-section steel 42 does not deteriorate.
The fire resistance performance of the composite beam 40 is the same as that of the composite beam 10, and the description thereof is omitted.
As described above, the composite beam 40 has a total height of the concrete slab 52 and the H-shaped steel 42 supporting the cleat slab 52, the thickness h of the concrete slab 52, and the thickness of the fireproof coating material. It can be reduced by s. That is, the ceiling area (not shown) can be lowered.

Next, the construction method of the composite beam 40 will be described.
As shown in FIG. 6A, first, the studs 24 are joined to the lower surface of the upper flange of the H-section steel 12 and both surfaces of the web 18, and the reinforcing bars 26 for preventing the fall are attached to the studs 24.

Next, the web formwork 34 is attached vertically on both sides of the web 48 of the H-shaped steel 42 with a gap h between the tip of the lower flange 46 of the H-shaped steel 42 and the upper surface of the upper flange 44. .
Thereafter, concrete is placed between the web formwork 34 and the web 48 to obtain a precast web concrete 50.

  After curing the precast web concrete 50, the H-section steel 42 to which the precast web concrete 50 is fixed is bridged between pillars (not shown).

  Next, the slab formwork 32 is laid except for a portion overlapping the upper flange 44 when seen in a plan view. After arranging the main reinforcement 54 and the distribution reinforcement 56, concrete is placed on the slab formwork 32. Concrete is also cast between the precast web concrete 50 and the lower surface of the upper flange 44 to form a concrete slab 52.

  At this time, the upper surface of the precast web concrete 50 can be used as a support member between the laying operation of the slab formwork 32 and the placing operation of the concrete slab 52, thereby improving workability.

(Third embodiment)
As shown in FIGS. 7 and 8, in the refractory building 60 according to the third embodiment, the composite beam 10 is connected to a column 62.
The column 62 is a hollow round or square steel pipe (round or square steel tube filled with concrete), and the periphery of the column 62 is surrounded by a column-beam joining member 65 having a joint portion 65A protruding in the beam direction. Thus, the column 62 and the column beam joining member 65 are directly joined. The H-shaped steel 12 is joined to the joint portion 65A of the column beam joining member 65 by welding or a bolt (not shown).

  The composite beam 10 has been described in the first embodiment, and a description thereof will be omitted. The upper surface of the upper flange of the beam-column joining member 65 has the same height as the upper surface of the concrete slab 20 and the upper surface of the upper flange 14.

  Thereby, also in the column beam joint, the total height of the concrete slab 20 and the H-section steel 12 supporting the cleat slab 20 can be reduced.

Next, an application example to the fireproof building 60 will be described.
As shown in FIG. 8A, in the configuration of the conventional concrete slab 20 and the H-section steel 12 that supports the cleat slab 20, the standard floor height is 4.0 m. For this reason, if the floor height of the first floor is 6.5 m, the building height is 34.5 m if the number of floors on the ground is eight. Considering the limitations of road diagonals and adjacent ground diagonals, the number of floors cannot be increased any further.

  On the other hand, as shown in FIG. 8B, in the composite beam 10, the floor height can be lowered by the thickness h of the concrete slab 20 and the thickness s of the fireproof coating as described above. For example, while maintaining the same height of the living space, the floor height can be reduced to 3.8 m by 0.2 m lower than the standard floor height of 4.0 m.

  As a result, even on a site with the same building conditions, if the height of the first floor is 6.5 m, the building height will be 36.9 m even if the number of floors is 9 floors, taking into account the limitations of the road diagonal line and the adjacent diagonal line Even within the allowable range.

  Thus, although it is the land of the same site, the number of floors, which has conventionally been the 8th floor, can be increased by 1 floor to be a 9th floor building. As a result, the floor area can be increased and the building materials can be reduced.

  Although the fireproof building 60 shown in FIGS. 7 and 8 has been described with the composite beam 10 according to the first embodiment, the composite beam 40 according to the second embodiment may be used.

It is a figure which shows the basic composition of the composite beam which concerns on the 1st Embodiment of this invention. It is a figure which shows the effect of the composite beam which concerns on the 1st Embodiment of this invention. It is a figure which shows the composite beam construction method of the composite beam which concerns on the 1st Embodiment of this invention. It is a figure which shows the basic composition of the composite beam which concerns on the 2nd Embodiment of this invention. It is a figure which shows the effect of the composite beam which concerns on the 2nd Embodiment of this invention. It is a figure which shows the composite beam construction method of the composite beam which concerns on the 2nd Embodiment of this invention. It is a figure which shows the basic composition of the fireproof building which concerns on the 3rd Embodiment of this invention. It is a figure which shows the example of application of the fireproof building which concerns on the 3rd Embodiment of this invention. It is a figure which shows the basic composition which makes the overlap dimension of the beam and slab of a prior art example low.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Composite beam 12 H-section steel 14 Upper flange 16 Lower flange 18 Web 20 Concrete slab 22 Web concrete 24 Stud 26 Reinforcement 32 Slab formwork 34 Web formwork 36 Concrete 40 Composite beam 60 Fireproof building

Claims (3)

An H-shaped steel, a stud joined to the lower surface of the upper flange of the H-shaped steel and the web of the H-shaped steel, a reinforcing bar attached to the stud, and a lower flange of the H-shaped steel. From the upper surface to the bottom of the stud joined to the lower surface of the upper flange , concrete is placed on both sides of the web, and the stud and the reinforcing bars joined to both sides of the web are embedded inside and cured. A precast web concrete beam member ,
A concrete slab in which concrete is placed on the upper surface of the precast web concrete so that the stud joined to the lower surface of the upper flange is embedded, and the upper surface of the upper flange of the H-shaped steel and the slab surface are flush with each other. When,
Composite beam with A stud is joined to the lower surface of the upper flange of the H-shaped steel and both sides of the web of the H-shaped steel, and reinforcing bars are attached to the stud, and the upper surface of the lower flange of the H-shaped steel is joined to the lower surface of the upper flange. The concrete is placed on both sides of the web up to the bottom of the studs so as to embed the studs and the reinforcing bars bonded to both sides of the web, and cured to form precast web concrete, A beam member process;
  Spanning the beam member between columns;
  The concrete is placed so that the stud joined to the lower surface of the upper flange is embedded in the upper surface of the precast web concrete so that the upper surface of the upper flange of the H-shaped steel and the slab surface are flush with each other. Forming a concrete slab on
  Composite beam construction method having A fireproof building in which the composite beam according to claim 1 or the composite beam constructed by the composite beam construction method according to claim 2 is connected to a column.

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