JP7271453B2 - hybrid beam structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hybrid beam structure that is excellent in workability and that can ensure sufficient reinforcement strength in the region where a beam end RC portion is switched to a steel frame beam.

Patent Documents 1 to 3 are known as technologies relating to a hybrid beam configured by embedding beam end portions of steel beams in beam end RC portions protruding from reinforced concrete columns. The "beam with reinforced concrete ends and a steel-framed central part" of Patent Document 1 consists of a central steel frame part and an end reinforced concrete part, and the steel frame of the central steel frame part is buried in a part of the end reinforced concrete part. In a beam formed by integrating both, a part of the main reinforcement of the reinforced concrete part is welded to the steel frame embedded in the same part, and the other part is a threaded reinforcing bar, and both sides sandwiching the steel frame part on the end face of the reinforced concrete part The end of the threaded reinforcing bar is tightened through a fixing plate and a nut, and the steel frame embedded in the reinforced concrete part and the reinforcing bar or spiral PC steel material are surrounded around the main reinforcing bar, and the steel frame is embedded in the reinforced concrete part. The reinforcing bars or spiral PC steel materials are arranged more densely at both ends of the portion than in the intermediate portion.

In Patent Literature 1, a fixing plate is provided on the end surface of the end reinforced concrete portion to tighten the threaded reinforcing bars.

Patent Document 2, "Method of Joining Precast Concrete Columns and Steel Beams", includes a U-shaped bracket portion on the stigma of a PC column so that the ends of the steel beams can be placed thereon, and the steel beams. Install a half PC column comprising a plurality of upper end main reinforcements and lower end main reinforcements connected to the end, then a band plate fitted to the end of the bracket part, the upper end main reinforcement and the lower end The end of the steel frame beam to which the fixing plate to which the main reinforcement is fixed is mounted on the bracket part of the half PC column, then the band plate is fitted to the tip part of the bracket part, The upper end main reinforcement and the lower end main reinforcement of the beam are fixed to the fixing plate, and concrete is poured into the U-shaped inside and upper part of the bracket part to construct the joint part between the bracket part and the steel beam. It is

In Patent Document 2, on the end face of the half PC column, the upper end main reinforcement and the lower end main reinforcement are fixed to a fixing plate, and the band plate is fitted to the half PC column.

In the "building with composite beams" of Patent Document 3, both ends of a steel frame spanned between opposing columns are covered with RC, the central portion of the steel frame is a steel beam, and both ends are RC beams. It is a building with hybrid (composite) beams that are reinforced with reinforcing bars at the ends of the beams on the column side and on the steel beam side. A steel-frame beam-side reinforcing part is provided at the end of the RC beam on the steel frame side so that a plastic hinge that deforms plastically during an earthquake does not occur in the RC beam. resulting plastic hinge region.

In Patent Document 3, RC beams are reinforced with main reinforcements and stirrups, and the arrangement of the stirrups is set to be coarse and dense.

JP-A-1-268947 JP-A-6-272311 JP 2013-170386 A

In a hybrid beam, the maximum stress is generated at the steel frame beam side tip of the beam end RC portion, which is the region where the beam end RC portion protruding from the reinforced concrete column is switched to the steel frame beam.

Even in the background art, the tip part is reinforced, but fixing the threaded reinforcing bar to the fixing plate on the end face, fixing the main reinforcing bar to the fixing plate on the end face, and fitting the band plate are is complicated and cannot be effectively reinforced in spite of the construction labor. There was a problem that it was difficult to sufficiently secure the reinforcement strength for the part.

The present invention has been invented in view of the above-mentioned conventional problems, and is a hybrid that is excellent in workability and at the same time can ensure sufficient reinforcement strength for the area where the beam end RC portion is switched to the steel frame beam. The purpose is to provide a beam structure.

A hybrid beam structure according to the present invention is a hybrid beam configured by embedding a beam end portion of a steel beam in a beam end RC portion protruding from a reinforced concrete column, wherein the beam end RC portion includes the beam end RC portion. A plurality of beam end main reinforcements are arranged so as to protrude from the reinforced concrete column in the longitudinal direction of the beam, and a plurality of beam end main reinforcements are formed in an annular shape surrounding the beam end from the outer periphery of the beam end main reinforcements. a plurality of beam end shear reinforcing bars arranged at intervals from the side of the reinforced concrete column toward the protruding side of the beam end main reinforcement in the beam end RC section; In the tip region of the protruding side of the beam end main reinforcing bar, an annular closed core reinforcing bar surrounding a plurality of the beam end main reinforcing bars individually on both sides in the beam width direction of the beam end is attached to each of the beam end shear reinforcing bars. It is characterized by being superimposed and arranged so as to form a pair.

The beam end shear reinforcing bars are densely arranged at narrow intervals in the tip region of the projecting side of the beam end main reinforcing bar, compared to other regions of the beam end main reinforcing bar.

In the base end region on the column side of the beam end main reinforcement close to the reinforced concrete column, the beam end shear reinforcing bars are densely spaced at narrower intervals than in the intermediate region between the base end region and the tip region. It is characterized by being reinforced.

In the base end region, core reinforcing bars forming an annular shape in pairs with the beam end shear reinforcing bars are individually arranged on both sides of the beam end portion in the beam width direction.

In the intermediate region, core reinforcing bars forming an annular shape in pairs with the beam end shear reinforcing bars are individually arranged on both sides of the beam end portion in the beam width direction.

The hybrid beam structure according to the present invention is excellent in workability, and at the same time, it is possible to ensure sufficient reinforcement strength for the region where the beam end RC portion is switched to the steel frame beam.

BRIEF DESCRIPTION OF THE DRAWINGS It is a partially broken schematic front view which shows an example of the building frame to which the hybrid beam structure which concerns on this invention is applied. 1 is a side sectional view of a beam end RC portion showing a preferred embodiment of a hybrid beam structure according to the present invention; FIG. FIG. 3 is an explanatory diagram illustrating a front cross section of a beam end RC portion shown in FIG. 2; Fig. 4(A) is a core bar, and Fig. 4(B) is a U-shaped bar. , and FIG. 4(C) is a diagram showing a cap muscle. FIG. 5 is an explanatory diagram for explaining reinforcing bars arranged in the tip region of the beam end RC portion shown in FIG. 2, FIG. 5(C) is a diagram showing a cap muscle. In FIG. 2, it is an A section enlarged view. FIG. 3 is an explanatory diagram for explaining a fixing piece provided at the beam end RC portion shown in FIG. 2; FIG. 3 is an explanatory diagram illustrating a first step of constructing the hybrid beam structure shown in FIG. 2; FIG. 3 is an explanatory diagram illustrating a second step of constructing the hybrid beam structure shown in FIG. 2; FIG. 3 is an explanatory diagram illustrating a third step of constructing the hybrid beam structure shown in FIG. 2; FIG. 4 is an explanatory diagram illustrating a fourth step of constructing the hybrid beam structure shown in FIG. 2; 3 is an explanatory diagram illustrating a fifth step of constructing the hybrid beam structure shown in FIG. 2; FIG. FIG. 10 is an explanatory view explaining a sixth step of constructing the hybrid beam structure shown in FIG. 2;

A preferred embodiment of a hybrid beam structure according to the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows a partially cut away schematic front view of a building frame 1 with hybrid beams.

A building frame 1 is constructed by constructing a steel beam 3 between a pair of left and right reinforced concrete columns 2 . On each reinforced concrete column 2, a beam end RC portion 4 is integrally formed with the reinforced concrete column 2 so as to protrude from the column-to-beam joint 2a along the construction direction of the beam. Left and right beam end portions 3a of the steel beams 3 constructed between the reinforced concrete columns 2 are embedded in beam end RC portions 4 of the reinforced concrete columns 2, respectively. Therefore, the beams of the building frame 1 are SRC-structured at the beam-end RC portions 4, and S-structured at intermediate portions between the beam-end RC portions 4. As shown in FIG. The upper surface of the beam end RC portion 4 is the floor level F.

FIG. 2 is a side sectional view of the beam end RC portion 4 in which one beam end portion 3a of the steel beam 3 is embedded, and FIG. 3 is a front sectional view of the beam end RC portion 4. FIG. A) is a cross-sectional view taken along the line BB in FIG. 2, and FIG. 3B is a cross-sectional view taken along the line CC in FIG.

The beam end RC portion 4 is configured by embedding a plurality of beam main reinforcing bars and shear reinforcing bars in concrete C, like a general RC beam.

Specifically, in the concrete C of the beam end RC portion 4, the beam ends 3a of the steel beams 3 embedded in the beam end RC portion 4 are surrounded from the outside, and are spaced appropriately apart from each other. , and a plurality of beam main rebars (hereafter referred to as beam end main rebars 5) including beam upper end main rebars and beam lower end main rebars.

The plurality of beam end main reinforcements 5 are arranged in the beam end RC portion 4 by protruding from the reinforced concrete column 2 in the beam length direction along the beam installation direction from the column-to-beam joint 2a.

A plurality of shear reinforcing bars embedded in the concrete C of the beam end RC portion 4 (hereinafter referred to as beam end shear reinforcing bars 6) surround the beam end portion 3a of the steel beam 3 from the outer periphery of the plurality of beam end main reinforcing bars 5. It is formed in an annular shape.

These multiple beam end shear reinforcing bars 6 are spaced apart from each other along the beam installation direction from the column-to-beam joint 2a toward the projecting side of the beam end main bars 5 from the reinforced concrete column 2 side. Reinforcement is arranged in 4.

When the steel beam 3 is erected, the steel beam 3 is suspended from above onto the beam end RC portion 4. Therefore, the beam end shear reinforcing bars 6 are shown in FIGS. As shown in (B) and (C) of the inside, the U-shaped rebar 7 with an open upper side so that the steel beam 3 to be lowered can be received, and after the steel beam 3 has been lowered, After the steel frame beam 3 is installed, the cap reinforcement 8 is tied to the U-shaped reinforcement 7 with a number wire to form a ring shape. ing.

The U-shaped reinforcement 7 and the cap reinforcement 8 are attached to the beam end main reinforcement 5 by hooking the folded portions 7a and 8a formed at the ends thereof to the beam end main reinforcement 5 at the upper end. The individual beam end main reinforcements 5 and the beam end shear reinforcing reinforcements 6 are also fixed to each other with a number wire.

Further, in the beam end RC portion 4, core reinforcements 9 and 10 shown in FIGS.

In the beam end RC portion 4, as shown in FIG. Towards the protruding side of the beam end main reinforcing bar 5, a tip region X on the protruding side of the beam end main reinforcing bar 5, a base end region Y on the column side of the beam end main reinforcing bar 5 adjacent to the reinforced concrete column 2, a base end region Y and a tip. Three areas of intermediate area Z between area X are set.

In the tip region X of the beam end RC portion 4, the beam end shear reinforcing bars 6 are densely arranged at narrow intervals (narrow pitch) compared to the base end region Y and the intermediate region Z.

In the proximal region Y, the beam end shear reinforcing bars 6 are densely arranged at narrower intervals (narrower pitch) than in the intermediate region Z. In the proximal region Y, the beam end shear reinforcing bars 6 may be arranged at approximately the same intervals as in the distal region X.

The reinforcement density is set high so as to increase the amount of reinforcing bars in the tip region X where the beam end RC portion 4 where the maximum bending stress is generated is switched to the steel frame beam 3, thereby effectively reinforcing the beam end RC portion 4. I have to.

In addition, since the tip of the beam end portion 3a of the steel frame beam 3 is buried as well as the joint fixed end of the beam structure, the base end region Y on the side of the reinforced concrete column 2 in which a large shear stress occurs also has a reinforcing bar amount The reinforcement density is set high so as to increase , and the beam end RC portion 4 is sufficiently reinforced.

To explain the core reinforcements 9 and 10 arranged in pairs with the beam end shear reinforcing reinforcement 6, in the tip region X, as core reinforcements, on both sides of the beam end portion 3a of the steel beam 3 in the beam width direction, A plurality of annular closed core reinforcements 9 surrounding a plurality of beam end main reinforcements 5 are arranged.

That is, as shown in FIG. 3(B), the closed core reinforcement 9 is positioned on one side of the beam end 3a in the beam width direction (the right side in the figure) of the beam end 3a. On the other side in the beam width direction (left side in the figure), it surrounds only the beam end main reinforcement 5 located on the other side of the beam end 3a. .

In other words, the closed core bars 9 are arranged on both sides of the beam end portion 3a of the steel frame beam 3 in the beam width direction so as to sandwich the beam end portion 3a from both sides.

As shown in FIG. 5(A), the closed core bar 9 is formed by bending a single reinforcing bar into a square shape and welding the opposing ends together by butting or overlapping them to form a seamless endless ring. formed in

A plurality of closed core reinforcements 9 are inserted so as to be sent from the projecting side tip 5a of the beam end main reinforcement 5 toward the reinforced concrete column 2 side, and the reinforcement for the beam end main reinforcement 5 is performed.

A plurality of closed core reinforcements 9 are provided, and each of the beam end shear reinforcements 6 arranged in the tip region X is overlapped and arranged. That is, the reinforcing bars of the closed core reinforcement 9 and the beam end shear reinforcing reinforcement 6 are arranged in a state of contact with each other in the longitudinal direction of the beam end main reinforcement 5 .

The closed core reinforcement 9 and the beam end shear reinforcement 6 which form a pair are bound with a wire. Fixed.

In the tip region X, the plurality of closed core reinforcements 9 formed by welding are pushed out to the outside by the flange of the steel beam 3 being bent to the beam end RC portion 4 by the bending that occurs in the steel beam 3. When the force acts, the beam end main reinforcement 5 that tries to move in the same direction is suppressed from the outside, and the stress generated in the beam end main reinforcement 5 is borne.

Further, in the tip region X, as shown in FIGS. 2 and 6, a fixing piece 11 is individually provided so as to cover the projecting side tip 5a of each beam end main reinforcement 5. As shown in FIG.

FIG. 6 is an enlarged view of part A in FIG. 7A and 7B are explanatory diagrams for explaining the fixing piece 11, FIG. 7A being a side view and FIG. 7B being a front view.

The fixing piece 11 has a nut portion 11a to be screwed onto the threaded portion of the beam end main reinforcement 5, and an external dimension that expands outward from the nut portion 11a. and a plate portion 11b that is fixed to the concrete C of the RC portion 4 and bears the stress.

At least one of a plurality of pairs of beam end shear reinforcing bars 6 and closed core bars 9 arranged in the tip region X, in the illustrated example, one of the positions closest to the steel beam 3 exposed from the beam end RC portion 4 A pair of one beam end shear reinforcing bar 6 and one closed core bar 9 is arranged around the beam end main bar 5 around the nut portion 11a of the fixing piece 11 thereof.

The projecting side tip 5a of the beam end main reinforcement 5 provided with the fixing piece 11 has a diameter larger than the diameter of the beam end main reinforcement 5 itself. Therefore, only the beam end shear reinforcing bars 6 and the closed core bars 9 that are hung on the fixing piece 11 have external dimensions that are slightly larger than the other beam end shear reinforcing bars 6 and the closed core bars 9 in the tip region X. formed by

As a result, at the projecting side tip 5 a of the beam end main reinforcement 5 , the fixing piece 11 is fixed to the concrete C, and the fixing piece 11 is held by the beam end shear reinforcement 6 and the closed core reinforcement 9 . The tip region X, which receives bending stress, is strongly reinforced.

In the intermediate region Z and the base end region Y, as shown in FIGS. A plurality of circular core reinforcements 10 are arranged. The core reinforcement 10 is arranged on both sides of the beam end portion 3a of the steel frame beam 3 in the beam width direction so as to sandwich the beam end portion 3a from both sides.

As shown in FIG. 4(A), the core reinforcement 10 is a reinforcing bar arranged vertically with folded portions 10a hooked to the beam end main reinforcements 5 at the upper and lower ends. The reinforcing bars are arranged so as to face the vertical portions 7b of the U-shaped bars 7 (see FIG. 4(B)) forming the bars 6 and extending in the vertical direction.

Then, as shown in FIG. 3A, the core reinforcement 10 is provided on one side of the beam end 3a in the beam width direction (the right side in the figure), and the beam end shear reinforcement 6 (the U-shaped reinforcement 7 and the cap reinforcement) 8) to form an annular shape and surround only the beam end main reinforcement 5 located on the one side of the beam end 3a. Combined with the end shear reinforcement 6 (the U-shaped reinforcement 7 and the cap reinforcement 8), it exhibits an annular shape and surrounds only the beam end main reinforcement 5 located on the other side of the beam end 3a.

The core reinforcement 10 is arranged on both sides of the beam end portion 3a of the steel frame beam 3 in the beam width direction so as to sandwich the beam end portion 3a from both sides. The core reinforcement 10 is bound and fixed to the paired cap reinforcements 8 and U-shaped reinforcements 7 of the beam end shear reinforcing reinforcements 6 and also to the beam end main reinforcements 5 with chain wires.

By providing the core reinforcement 10 in pairs with respect to the beam end shear reinforcing reinforcement 6, an annular reinforcing structure surrounding the concrete C on both sides of the beam end 3a is secured and the amount of reinforcement is increased. there is

Next, a method for constructing a hybrid beam will be described in detail with reference to FIGS. 8 to 13. FIG. 8A and 8B are explanatory diagrams for explaining the first step, FIG. 8A is a side view, and FIG. 8B is a view taken along line DD in FIG. 8A.

In the first step, a plurality of beam end main reinforcements 5 are arranged at the construction position of the beam end RC portion 4 so as to protrude from the reinforced concrete column 2 in the beam length direction.

The beam end main reinforcing bar 5 has the other end 5b in the length direction located in the column-to-beam joint 2a of the reinforced concrete column 2 with respect to the tip 5a on the projecting side.

Of all the beam end main rebars 5, except for the beam end main rebars 5 at the upper end arranged on the beam end 3a, the beam end main rebars 5 are arranged so as to avoid the lowering space S of the beam end 3a of the steel beam 3 to be lowered. Reinforced.

9A and 9B are explanatory diagrams for explaining the second step, FIG. 9A is a side view, FIG. 9B is a view taken along line EE in FIG. C) is a view taken along line FF in FIG. 9(A).

In the second step, a plurality of U-shaped reinforcements 7, a plurality of closed core reinforcements 9, and a core reinforcement 10 are laid out.

The U-shaped reinforcements 7 surrounding the plurality of beam end main reinforcements 5 from below are directed from the reinforced concrete column 2 side to the projecting side of the beam end main reinforcements 5 for all the regions of the base end region Y, the middle region Z and the tip region X. Reinforcement is arranged at intervals.

Annular closed core reinforcements 9 individually enclosing a plurality of beam end main reinforcements 5 on both sides of the suspension space S in the beam width direction are arranged in pairs for each of the plurality of U-shaped reinforcements 7 arranged in the tip region X. Reinforcement is arranged by superimposing so as to form

Specifically, a plurality of closed core reinforcements 9 are inserted in advance from the projecting side tip 5a of the beam end main reinforcement 5 toward the reinforced concrete column 2 side, and then each closed core reinforcement 9 is paired with the closed core reinforcement. After arranging the U-shaped muscles 7, the intervals between the closed core muscles 9 are adjusted.

At this time, since the fixing piece 11 is installed on the projecting side tip 5a of the beam end main reinforcement 5 after the fourth step to be described later, the U-shaped reinforcement 7 and the closed core reinforcement 9 in the range that hinders this work are It is desirable that the reinforcing pieces are grouped slightly closer to the proximal end and that the reinforcing pieces are arranged at a predetermined position after the fixing piece 11 is installed.

Further, core reinforcements 10 are individually arranged on both sides of the suspension space S in the beam width direction for each of the U-shaped reinforcements 7 in the intermediate region Z and the base end region Y.

10A and 10B are explanatory diagrams for explaining the third step, FIG. 10A is a side view, FIG. C) is a view taken along line HH in FIG. 10(A).

In the third step, the steel frame beam 3 is lowered and the beam end portion 3a of the steel frame beam 3 is installed in the lowering space S.

11A and 11B are explanatory diagrams for explaining the fourth step, FIG. 11A is a side view, and FIG. 11B is a view taken along the line II in FIG. 11A.

In the fourth step, the beam end main reinforcement 5 is additionally arranged above the beam end 3a so as to surround the beam end 3a of the steel frame beam 3 together with the beam end main reinforcement 5 already arranged in the first step. .

The beam end main reinforcement 5 is arranged at the construction position of the beam end RC portion 4 so as to protrude from the reinforced concrete column 2 in the length direction of the beam.

These beam end main bars 5 also have the other end 5b in the length direction located in the column-to-beam joint 3a of the reinforced concrete column 2 with respect to the projecting side tip 5a.

After the fourth step, as shown in FIG. 11, the fixing piece 11 is provided so as to cover the protruding side tip 5a of the beam end main reinforcement 5. As shown in FIG.

12A and 12B are explanatory diagrams for explaining the fifth step, FIG. 12A is a side view, FIG. C) is a view taken along line KK in FIG. 12(A).

In the fifth step, a cap reinforcement 8 is arranged from above the U-shaped reinforcement 7, and an annular beam end shear reinforcing reinforcement 6 surrounding the beam end 3a of the steel beam 3 is attached from the outer periphery of the plurality of beam end main reinforcements 5. Form.

After the fifth step, in the tip region X, as shown in FIG. At least one pair of the mold core reinforcements 9 is laid around the outer periphery of the nut portion 11a of the fixing piece 11 to arrange the reinforcements.

As described above, the beam end shearing reinforcement 6 and the closed core reinforcement 9 that are hung on the fixing piece 11 are formed to be one size larger than the others.

13A and 13B are explanatory diagrams for explaining the sixth step, FIG. 13A is a side cross-sectional view, FIG. 13(C) is a cross-sectional view taken along line MM in FIG. 13(A).

In the sixth step, the beam end portion 3 a of the steel beam 3 , the beam end main reinforcement 5 , the beam end shear reinforcement 6 , the core reinforcement 10 , and the closed core reinforcement 9 are combined with the beam-to-column joint 2 a of the reinforced concrete column 2 . A formwork 12 is installed so as to surround it from the inside of this formwork 12, and a series of concrete C is poured into the formwork 12 from the reinforced concrete column 2 side. is constructed.

In the hybrid beam structure according to the present embodiment described above, in the tip region X of the beam end RC portion 4 on the projecting side of the beam end main reinforcement 5, on both sides of the beam end portion 3a of the steel beam 3 in the beam width direction, Individually, the annular closed core reinforcement 9 surrounding the beam end main reinforcement 5 is superimposed on each of the beam end shear reinforcing reinforcements 6 so as to form a pair, so that the steel beam 3 When the flange of the steel frame beam 3 exerts a force to push the beam end RC portion 4 to the outside due to bending, the beam end main reinforcement 5 that tries to move in the same direction by the force acts on the beam end RC portion 4. It can be suppressed by the closed core reinforcement 9, and the stress generated in the beam end main reinforcement 5 can be effectively borne by these closed core reinforcements 9 to ensure sufficient reinforcement strength.

In the tip region X on the protruding side of the beam end main reinforcing bar 5, the beam end shear reinforcing bars 6 are densely arranged at narrow intervals compared to the other regions Y and Z of the beam end main reinforcing bar 5, Since the reinforcement density is set high so as to increase the amount of reinforcing bars effective against the stress generated in the tip region X where the beam end RC portion 4 where the maximum bending stress is generated is switched to the steel frame beam 3, this increases the beam end RC The portion 4 can be effectively reinforced.

In the base end region Y, the beam end shear reinforcing bars 6 are densely arranged at narrower intervals than in the middle region Z. Since the tip of the portion 3a is buried, the reinforcement density is increased so as to increase the amount of reinforcing bars effective against the stress generated in the base end region Y on the side of the reinforced concrete column 2 where a large shear stress occurs. Since it is set high, the beam end RC portion 4 can be sufficiently reinforced.

In the base end region Y, since the ring-shaped core reinforcement 10 paired with the beam end shear reinforcement 6 is individually arranged on both sides of the beam end 3a in the beam width direction, concrete is formed on both sides of the beam end 3a. An annular reinforcing structure surrounding C can be secured, and an excellent reinforcing effect can be obtained by increasing the amount of reinforcing bars.

In the intermediate region Z, since the core reinforcement 10 paired with the beam end shear reinforcement 6 is individually arranged on both sides of the beam end 3a in the beam width direction, the concrete C is formed on both sides of the beam end 3a. It is possible to secure an annular reinforcing structure surrounding the , and to increase the amount of reinforcing bars effective against the stress generated in this area, thereby obtaining an excellent reinforcing effect.

In addition, in this embodiment, the fixing piece 11 is provided so as to cover the projecting side tip 5a of the beam end main reinforcement 5, and at least one of the plurality of pairs of the beam end shear reinforcing reinforcement 6 and the closed core reinforcement 9 is attached to a plurality of beams. Since the end main reinforcement 5 is arranged around the outer circumference of the nut portion 11a of the fixing piece 11, at the projecting side tip 5a of the beam end main reinforcement 5, the fixing piece 11 is fixed to the concrete C and the beam end is sheared. By holding the fixing piece 11 by the reinforcing bar 6 and the closed core bar 9, the tip region X of the steel beam 3, which receives a large bending stress, can be strongly reinforced.

Furthermore, in the construction method of the hybrid beam according to the present embodiment, the hybrid beam exhibiting the above-described excellent effects is adapted to the work of suspending the steel frame beam 3 to the beam end RC portion 4, and excellent workability can be achieved. It can be constructed smoothly.

2 Reinforced concrete column 3 Steel beam 3a Beam end of steel beam 4 Beam end RC part 5 Beam end main reinforcement 6 Beam end shear reinforcement 9 Closed core reinforcement 10 Core reinforcement X Tip region Y Base end region Z Intermediate region

Claims (5)

A hybrid beam constructed by embedding a beam end portion of a steel frame beam in a beam end RC portion protruding from a reinforced concrete column,
a plurality of beam end main bars arranged in the beam end RC portion in an arrangement surrounding the beam end portion so as to protrude from the reinforced concrete column in the longitudinal direction of the beam;
It is formed in an annular shape surrounding the beam end portion from the outer periphery of the plurality of beam end main reinforcements, and is arranged in the beam end RC portion at intervals from the reinforced concrete column side toward the projecting side of the beam end main reinforcement. with a plurality of beam end shear reinforcements,
In the tip region of the beam end RC portion on the protruding side of the beam end main reinforcement, an annular closed core reinforcement individually surrounding the plurality of beam end main reinforcements on both sides of the beam end in the beam width direction. , a hybrid beam structure characterized in that each of the beam end shear reinforcing bars is arranged so as to overlap each other so as to form a pair. 3. The beam end shear reinforcing bars are densely arranged at narrow intervals in the tip region of the protruding side of the beam end main bar compared to other regions of the beam end main bar. 2. The hybrid beam structure of claim 1. In the base end region on the column side of the beam end main reinforcement close to the reinforced concrete column, the beam end shear reinforcing bars are densely spaced at narrower intervals than in the intermediate region between the base end region and the tip region. 3. A hybrid beam structure according to claim 1 or 2, characterized in that it is reinforced. 4. The method according to claim 3, wherein, in the base end region, core reinforcing bars forming an annular shape in pairs with the beam end shear reinforcing bars are individually arranged on both sides of the beam end portion in the beam width direction. hybrid beam structure. 5. The method according to claim 3 or 4, characterized in that, in the intermediate region, core reinforcing bars forming an annular shape in pairs with the beam end shear reinforcing bars are individually arranged on both sides of the beam end portion in the beam width direction. Hybrid beam construction as described.

Images