KR101548114B1 - Steel concrete composite beam having increased composite effect of connecting part at the cross-section change part - Google Patents

Abstract

According to the present invention, a composite beam reduces a buried depth of a steel frame while improving a composite performance of a joint; improves rigidity of a boundary of a steel frame-PC composite area and a PC area; effectively controls cracks; significantly reduces a welding operation between a stirrup rebar and a joint, which is conventionally carried out in a PC factory; allows a bolting operation of a beam to a column or a wall without hindrance caused by the stirrup rebar; and improves torsion resistance and safety during installation by closing the stirrup rebar at the end of the beam.

Description

In this study, we investigated the effect of reinforced concrete composite beams on the cross-section change of steel beams.

The present invention relates to a steel-concrete composite beam, and more specifically, it can reduce the length of a steel frame to be buried while increasing the effect of the joining portion and increase the stiffness of the boundary portion between the steel-PC composite portion and the PC portion, This can significantly reduce the welding work of the steel reinforcing bars and joints that have already been done in the PC factory and the steel reinforcing bars do not interfere with the bolting operation to connect the beams to columns or walls, The reinforced bars are made to be closed type to improve torsional resistance and safety during construction.

Generally, it is a structure that is installed to be connected to a column or other beam to support the load transmitted from the slab.

FIG. 1 is a perspective view showing an example of such a beam, and FIG. 2 is a sectional view showing the beam. The beam 1 has a concrete member 2 formed to be long in the longitudinal direction, a connecting portion 3 provided at both ends of the concrete member 2 and a vertical stirrup reinforcing bar 4.

Among the above components, the connecting portion 3 is formed by embedding H-shaped steel in both ends of the concrete member 2, and a bolt hole for coupling with the column is formed on the web at the end of the H-shaped steel.

Since the beams 1 are provided at the both ends of the connection part 3 made of steel, they are advantageous in that they can be easily connected to the steel column as compared with the conventional RC beams.

However, the beam (1) has a problem that the connection portion (3) can be pulled out when a load is applied.

Also, the beam 1 has a problem that the rigidity rapidly changes at the boundary between the steel frame-PC composite section and the PC section. The boundary portion may be formed by the S.T.M. This corresponds to zone D (stress disturbance zone) classified as dangerous section for shear at the time of analysis.

In order to solve such a problem, the steel reinforcing bar 4 is densely arranged at the boundary portion, but the shearing force acting in the vertical direction is not effective.

On the other hand, the stirrup reinforcing bar 4 protrudes above the concrete member 2 so as to be integrated with the slab concrete (not shown in the figure). Since the stirrup reinforcement 4 is installed at both ends of the beam, it is not necessary to have a space for the operator to sit on the stud 4 due to the stud reinforcement 4 during the bolt operation for connecting the beam 1 to the column (not shown in the figure) .

In order to solve such a problem, a protruding portion of the stirrup reinforcing bar near the end portion is bent to form a closed struc- ture, thereby creating a working space. Then, after completing the bolt work, the reinforcing bar 4 is stretched vertically do. However, there is a problem in that the stirrup reinforcing bar 4 may lose strength or be broken while repeating the process of bending and stretching the stirrup reinforcing bar 4. [

In addition, the connection 3 is manufactured at a steel mill and then transferred to a PC (precast concrete) plant. However, in many cases, welding experts do not reside in the PC factory. Therefore, it is difficult to secure the welding quality when the connection portion 3 and the stirrup reinforcing bar 4 are welded together. If the welding is performed in the PC factory, . For example, if the lower flange of the connection 3 is located at the lower end of the section of the concrete or close to the lower end, the stirrup reinforcement 4 must be welded to the web, It is difficult to secure the welding quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an object to provide a steel-concrete composite beam capable of increasing a composite effect of a connecting portion and reducing a length of a steel-framed structure.

It is still another object of the present invention to provide a composite concrete composite beam capable of preventing a connection portion from being pulled out.

It is still another object of the present invention to provide a steel-concrete composite beam capable of enhancing the rigidity of a cross-sectional change portion (a boundary portion between a steel-PC composite section and a PC section) and efficiently controlling cracks.

It is another object of the present invention to provide a composite concrete beam of a steel frame, which is capable of remarkably reducing the welding work of the stirrup reinforcement and the connecting portion which have been conventionally performed in the PC factory.

Another object of the present invention is to provide an improved steel composite concrete beam so that the steel reinforcing bars do not interfere with the bolting operation for connecting the beam to a column or a wall.

It is another object of the present invention to provide an improved reinforced concrete composite beam which is improved in torsional resistance and safety by making a stirrup reinforcing bar closed at the ends of the beam.

In order to solve the above problems, a steel-concrete composite according to the present invention includes: a concrete member 10 formed to be long along a longitudinal direction of a beam; And a connection part 30 provided at both ends of the concrete member 10 and partially embedded along the longitudinal direction. The connecting portion 30 is for connecting the beam to a column or a wall or another beam or the like.

Vertical members 50 and 52 are installed on both sides of the web 33. Vertical members 50 and 52 are installed to connect the upper flange 31 and the lower flange 32 together.

Horizontal reinforcing bars 60 and 65 are connected to the vertical members 50 and 52 and horizontal reinforcing bars 60 and 65 are buried horizontally in the concrete. And it is possible to increase the stiffness of the boundary between the steel-PC composite section (the section where the connection section is embedded in the concrete) and the PC section, and to control the cracks efficiently.

The number of the vertical members 50 and 52 and the number of the horizontal reinforcing bars 60 and 65 installed in the vertical members 50 and 52 can be increased or decreased as needed.

Both ends of the horizontal reinforcing bars 60 and 65 are bent in a hook shape and the hooks are connected to the vertical members 50 and 52 on both sides of the web 33 and the center of the horizontal reinforcing bars 60 and 65 It is preferable to extend further toward the center of the web than the end of the web 33. The extended length is preferably sufficient for reinforcing the boundary portion with sufficient pull-out resistance.

As an alternative to the structure of the horizontal reinforcing bars 60 and 65, one end of the horizontal reinforcing bars is bent into a hook shape and connected to the vertical members 50 and 52 and the other end of the horizontal reinforcing bars is connected to the web 33 But may extend further toward the center of the beam than the end.

According to the present invention, the lower flange 32 is coincident with or in close proximity to the lower surface of the concrete member 10, and the stirrup is made to be closed while welding of the stirrup reinforcing bar and the connecting portion 30 is not necessary, A lower slot 37 through the web 33 is formed horizontally below the column 33 of the web 33 so as not to protrude above the concrete member and the upper portion of the web 33 37), an upper elongated hole 38 passing through the web 33 is formed horizontally. A stirrup reinforcing bar (70) penetrates the upper and lower long holes (38) and (37).

The stirrup reinforcing bar 70 does not protrude from the concrete over the interval of 300 mm to 500 mm from the end of the pillar of the connecting portion 30 due to the structure in which the stirrup reinforcing bar 70 passes through the upper long hole 38. Accordingly, since the space for the operator to sit on is provided in the section, bolt fastening operation (bolt fastening operation for connecting the beam to a column or the like) is provided.

Specifically, the stir bar reinforcement 70 may be formed by assembling the lower stir bar reinforcement 71 and the upper stirrup reinforcement 75.

The lower stirrup reinforcing bar 71 is bent in a hook shape such that the central portion of the lower stirrup reinforcing bar 71 passes through the lower long hole 37 and both ends of the lower stirrup reinforcing bar 71 extend over the upper cast steel rope 11. In order to install the lower stirrup reinforcement 71 in the lower elongated hole 37, the lower stirrup reinforcement 71 is laid down so that it passes through the lower elongated hole 37 from either end of the both ends, So that the hooks at both end portions span the upper cast steel rope 11.

The upper stirrup reinforcing bar 75 is bent in a hook shape such that its central portion passes through the upper elongated hole 38 and both ends of the upper reinforcing steel rod 75 span the upper casting steel rope 11. In order to install the upper stirrup reinforcement 75 in the upper elongated hole 38, the upper stirrup reinforcement 75 is laid down so as to pass through the upper elongated hole 38 from either end of the both ends, So that the hooks at both end portions span the upper cast steel rope 11.

As described above, the upper and lower stirrup reinforcing bars 75 and 71 are closed so that both end portions of the upper and lower stirrup reinforcing bars 75 and 71 are disposed to cover the upper cast steel rope 11. In addition, the closed stirrup of such a step increases the resistance to torsion and the safety at the time of construction.

A lower groove 39 penetrating through the web 33 is horizontally formed at the lower end of the opposite end of the web 33 on the opposite side of the column. And a stirrup reinforcing bar (90) penetrates the lower groove (39). In order to reinforce the boundary portion, two stirrup reinforcing bars 90 may be installed in close contact with each other.

A stirrup reinforcing bar 80 may be installed on both sides of the web between the lower groove 39 and the lower longitudinal hole 37. One end of the stirrup reinforcing bar 80 is vertically bent to abut the side surface of the web and the other end of the stirrup reinforcing bar 80 protrudes onto the concrete.

The present invention has the following effects.

First, the combined effect of the connecting portion 30 can be increased and the length of embedding of the steel frame can be reduced.

Secondly, it is possible to prevent the connection portion 30 from being pulled out.

Third, it is possible to increase the stiffness of the cross-section change portion (the boundary portion between the steel-PC composite section and the PC section) and to control cracks efficiently. In particular, the present invention can effectively resist the horizontal direction shear force and the vertical direction shear force by providing the vertical stirrup reinforcing bars 90 and the horizontal reinforcing bars 60 and 62 in the boundary portion.

Fourth, it is possible to significantly reduce the welding work of the stirrup reinforcement and the joints, which had previously been done in the PC factory.

Fifth, it is possible to prevent the stub reinforcement from interfering with bolts for connecting beams to pillars or walls. In the present invention, since the stirrup reinforcing bar 70 is installed to penetrate through the connecting portion 30 at the end of the beam, the stirrup reinforcing bar 70 does not protrude above the concrete, thereby providing a space for the bolt work at the end of the beam , It is possible to prevent the operator from falling down due to stub reinforcement.

Sixth, it is possible to increase the torsional resistance and safety at construction by making the stirrup reinforcement closed at the end of the beam.

1 is a perspective view showing an example of a beam according to the prior art;
Fig. 2 is a sectional view showing the beam of Fig. 1; Fig.
3 is a perspective view showing a composite beam according to a preferred embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a connection portion, a concrete member, and a reinforcing bar provided in the composite beam shown in FIG. 3;
FIG. 5 is a perspective view showing a connection part and a vertical member provided in the composite beam shown in FIG. 3; FIG.
Figure 6 is a front view showing the connection and vertical members of Figure 5;
Fig. 7 is a plan view showing a configuration in which a horizontal reinforcing bar is installed in the vertical member of Fig. 5; Fig.
8 is a front view showing a modification of the vertical member according to the present invention.
9 is a plan view showing a configuration in which a horizontal reinforcing bar is installed in the vertical member of Fig.
10 is a sectional view taken along the line AA 'of FIG.
11A is a view showing a lower stirrup reinforcing bar installed so as to penetrate a lower slot of a connecting portion.
11B is a view showing an upper stirrup reinforcing bar installed so as to penetrate the upper slot of the connecting portion.
12 is a cross-sectional view taken along line BB 'of FIG. 4;
13 is a view showing a stirrup reinforcing bar provided on both sides of a connecting portion.
14 is a cross-sectional view taken along line CC 'in Fig. 4;
15 is a view showing a stirrup reinforcing bar installed in a lower groove of a connecting portion;

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely examples of the present invention and are not intended to represent all of the technical ideas of the present invention, so that various equivalents And variations are possible.

FIG. 3 is a perspective view showing a composite beam according to a preferred embodiment of the present invention, and FIG. 4 is a sectional view showing a connection portion, a concrete member and a reinforcing bar provided in the composite beam.

The composite beam 100 includes a concrete member 10, a connecting portion 30 provided at both ends of the concrete member 10, a vertical member 50 provided at the connecting portion 30, (Not shown).

The concrete member 10 is a long member formed along the longitudinal direction of the beam 100. The concrete member 10 can be made in a precast manner.

The upper cast iron core 11, the lower cast iron core 12 and the tensile root 13 may be embedded in the concrete member 10.

The upper cast steel rope 11 is arranged long along the longitudinal direction of the beam at the upper part of the concrete member 10 and the lower cast steel rope 12 is arranged at a longer length along the longitudinal direction of the beam at the lower part of the concrete member 10.

The tensile roots 13 are arranged long along the longitudinal direction of the beams at the bottom of the concrete member 10, and the tensile rods 13 may be prestressed.

4, the concrete member 10 is indicated by a dotted line in order to facilitate understanding of the internal structure of the concrete member 10. As shown in FIG. Although the connecting portions 30 are provided on both ends of the concrete member 10 in the figure, the connecting member 30 may be provided between both ends of the concrete member 10 to be connected to other beams . For example, a steel frame (not shown in the figure) or an iron plate (not shown in the drawings) for connecting other beams to each other may be embedded in the concrete between the both ends.

The connection part 30 is installed at both ends of the beam 100 in the longitudinal direction of the beam 100, and a part of the connection part 30 is buried in the concrete member 10. The connecting portion 30 may be steel bonded or pin bonded to a column or a wall or other beam (not shown in the drawings).

As shown in Figs. 5 and 6, the connecting portion 30 has an upper flange 31, a lower flange 32 and a web 33. The connection 30 can be made of a conventional steelmaking material (metal).

The upper flange 31 and the upper end of the web 33 may protrude above the concrete member 10 and this structure serves to integrate the beam 100 and the slab concrete (not shown). On the other hand, the upper flange 31 may coincide with the upper surface of the concrete member 10.

The lower flange 32 is installed so as to coincide with the lower surface of the concrete member 10. This structure increases the height of the web 33 so that the rigidity, shear strength and flexural strength of the connection portion 30 can be increased.

In addition, the structure facilitates installation of the connection 30 in a mold. That is, since the lower flange 32 is simply placed on the bottom of the mold, a member for separating the lower flange 32 from the bottom of the mold up and down is unnecessary.

The web 33 connects the upper and lower flanges 31 and 32. A plurality of stud bolts 34 may be provided on both sides of the web 33. The stud bolt 34 integrates the connection portion 30 with the concrete member 10 and prevents the connection portion 30 from being pulled out.

A plurality of bolt holes (35) are formed in an end portion of the web (33) on the column side. A bolt (not shown) for connecting the beam 100 to a column (not shown in the drawing) is fastened to the bolt hole 35.

A stiffener 36 is provided on both sides of the web 33 at a position slightly more toward the center than the bolt holes 35 so as to be perpendicular to the web 33 and the upper and lower flanges 31 and 32. The stiffener 36 prevents buckling or twisting of the connecting portion 30, and acts as a mold when pouring concrete.

The stiffener 36 is provided with a through hole 36a and a groove 36b. In order to apply the prestress to the tension roots 13, the tension roots 13 are provided so as to pass through the through holes 36a and the grooves 36b, and then the concrete is placed in a state where the tension roots 13 are applied with a prestress When the concrete is hardened, the portion extending outside the stiffener 36 is cut.

On the other hand, a lower elongated hole 37 is horizontally formed on the lower side of the column of the web 33. As shown in Fig. 4, a stirrup reinforcing bar 70 is installed in the lower longitudinal hole 37. As shown in Fig. As shown in Figs. 10 and 11A and 11B, the stirrup reinforcing bar 70 is assembled such that the lower reinforcing bar 71 and the upper reinforcing bar 75 form a closed stirrup.

Since the lower flange 32 is coincident with the lower surface of the concrete member 10, the lower long hole 37 is formed in the web 33 and the lower stirrup reinforcing bar 71 penetrates through the lower long hole 37 Eliminating the need to weld the web 33 and stirrup reinforcement in a PC (precast concrete) plant. For reference, if the lower flange 32 coincides with the underside of the concrete member 10, the stub reinforced bar can not pass through the web, so that it must be welded to the lower flange or web if there is no lower slot 37.

As described above, there are many cases where the welding worker does not reside in the PC factory, and the cost increases when the welding is performed in the PC factory. The above-described construction of the present invention prevents the welding at the PC factory.

Preferably, an upper elongated hole 38 may be formed on the upper side where the lower elongated hole 37 is formed. That is, the upper elongated hole 38 may be formed horizontally on the upper side of the column of the web 33. The upper and lower elongated holes 38 and 37 are elongated in the transverse direction and formed into a slot having a low height in order to facilitate insertion of the upper and lower stirrup reinforcing bars 75 and 71 while minimizing the loss of shear resistance to be.

As shown in Figs. 10 and 11B, the upper slot 38 is provided with an upper strand reinforcing bar 75. Fig.

Both end portions of the upper and lower stirrup reinforcing bars 75 and 71 are bent in the form of hooks and spanned over the upper casting steels 11.

The structure in which the reinforcing bars 70 are composed of the upper and lower reinforcing bars 75 and 71 and the reinforcing bars 75 and 75 are formed horizontally longer than the upper reinforcing bars 75, So that it can be easily inserted into the upper slot 38 and the lower slot reinforcing bar 71 can be inserted into the lower slot 37 easily.

For example, in order to install the upper strand reinforcing bar 75 in the upper slot 38, the upper strand reinforcing bar 75 is laid sideways so as to be inserted from one of the hook portions (bent portions at both ends) After that, the upper strand reinforcing bar (75) is rotated and set up vertically.

In order to install the lower reinforcing bars 71 in the lower elongated holes 37, the lower reinforcing bars 71 are laid sideways and inserted from either one of the hooks (bent portions at both ends) The central portion of the reinforcing bar 71 is positioned at the lower longitudinal hole 37, and then the lower reinforcing bar 71 is rotated to stand vertically.

Since the stirrup reinforcing bars 70 are installed to be inserted into the upper long holes 38 to form the closed stirrups, the stirrup reinforcing bars 70 do not protrude above the concrete in a section of about 300 mm to 500 mm from the ends of the beams. Accordingly, the concrete member 10 is formed with a space in which a worker who performs a bolt fastening operation (bolt operation for connecting beams to a column or a wall, etc.) can be seated, and the worker is not disturbed by the stirrup reinforcing bar 70.

In addition, the closed-type stirrup improves the safety of the beam because it increases resistance and safety against twisting occurring at the time of construction.

Stroke reinforcing bars 80 are provided at the center of the beam slightly above the upper and lower long holes 38 and 37. 12 and 13, one end of the stirrup reinforcing bar 80 is welded to the web 33 and the other end of the stirrup reinforcing bar 80 protrudes above the concrete member 10, Is made when fabricating the connection part (30) in a steel frame factory.

As an alternative to the welding, the stirrup reinforcing bars 80 may be joined to the cast iron ropes 11 and 12 by wire or the like so that one end of the stirrup reinforcing bar 80 is in close contact with the web 33. [

A bottom groove 39 is formed at the end of the web 33 (i.e., the opposite end of the column). 4 and 6, the lower groove 39 may be formed by horizontally recessing the end of the web 33 by a predetermined length.

A stirrup reinforcing bar (90) is installed in the lower groove (39). As shown in Figs. 14 and 15, the stirrup reinforcing bar 90 is installed to penetrate through the lower groove 39, and both ends thereof are installed to protrude above the concrete.

Two stirrup reinforcing bars 90 can be installed in close proximity to the lower groove 39 and the lower groove 39. The reinforcing bars 90 can be formed in a steel-plastic composite section (i.e., a section in which the connecting section is buried in concrete) To reinforce the boundary of the section. As an alternative to the configuration in which the two stirrup reinforcing bars 90 are installed so as to be in close contact with each other, the stirrup reinforcing bars 90 may be provided more densely than the other portions.

On the other hand, at the boundary between the steel-PC composite section and the PC section, the stiffness is rapidly changed and the S.T.M. This corresponds to zone D (stress disturbance zone) classified as dangerous section for shear at the time of analysis. The present invention includes a vertical member (50) and a horizontal reinforcing bar (60) together with the above construction of the stirrup reinforcing bars (90) to reinforce the boundary portion. The vertical member 50 and the horizontal reinforcing bar 60 resist more effectively than the vertical reinforcing bars against the shear force acting in the vertical direction.

The vertical member 50 is provided on both sides of the web 33 and is provided to connect the upper and lower flanges 31 and 32 to each other. The vertical member 50 is installed so as to be perpendicular to the upper and lower flanges 31 and 32. Herein, 'vertical' refers to not only the vertical in the mathematical sense but also the pulling force transmitted from the horizontal reinforcing bar 60, But also inclined slightly to the extent that they can be easily transmitted to the flanges 31 and 32.

The upper end of the vertical member 50 is welded to the upper flange 31 and the lower end of the vertical member 50 is welded to the lower flange 32. As the vertical member 50, a steel bar, a steel pipe, a reinforcing bar, an iron plate, an angle, or the like may be used.

The horizontal reinforcement 60 is installed in the vertical member 50 in the horizontal direction. The horizontal reinforcing bar 60 can reduce the length of embedding of the steel frame (connecting portion) while enhancing the combining effect of the connecting portion 30. Further, the horizontal reinforcing bar 60 enhances the stiffness of the section change portion (the boundary portion between the steel frame-PC composite section and the PC section) and enables the crack to be efficiently controlled. In addition, the horizontal reinforcing bar 60 serves to prevent the pulling out of the connecting portion 30 and to resist the shearing force in the vertical direction.

In horizontal reinforcement, 'horizontal' means not only horizontal in mathematical sense but also inclined to be slightly inclined within a range that can resist the pulling force in unison with concrete and can effectively resist vertical direction shear force.

As shown in Figs. 4 and 7, both ends of the horizontal reinforcing bar 60 are bent to be connected to the vertical member 50 so as to form a hook. And, the center of the horizontal bar 60 extends further toward the center of the beam than the end of the web 33, which is preferably enough to resist the drawing.

As an alternative to the above construction of the horizontal reinforcement 60, one end of the horizontal reinforcement is bent so as to form a hook and connected to the vertical member 50 and the other end of the horizontal reinforcement is connected to the end of the web 33 Can be further extended toward the center of the beam. In this case, different horizontal reinforcing bars are connected to the respective vertical members 50, respectively.

6 and 7 show that the vertical member 50 is provided on each side of the web 33, but the number of the vertical members 50 can be increased as needed. 8 and 9 illustrate that two vertical members 50 and 52 are provided on both sides of the web 33 and horizontal reinforcing bars 60 and 65 are provided on the vertical members 50 and 52, ) Are combined. At this time, the horizontal member 65 may extend to the same point as the horizontal member 60 toward the center of the beam.

9 shows a structure in which a horizontal reinforcing bar 60 is installed on a vertical member 50 and a horizontal reinforcing bar 65 is installed on a vertical member 52. In the vertical member 50, And the horizontal reinforcing bars 65 may be provided only on the vertical member 52. [

10: concrete member 30:
50, 52: vertical member 60, 65: horizontal reinforcement
70, 80, 90: stirrup reinforcement 100: beam

Claims (7)

And a connecting portion 30 in which a portion of the concrete member 10 is buried along the longitudinal direction at both ends of the concrete member 10, (31), a lower flange (32) and a web (33)
A vertical member installed to connect the upper flange 31 and the lower flange 32 at both sides of the web 33; And
And a horizontal reinforcing bar horizontally connected to the vertical member,
The horizontal reinforcing bars extend further toward the center of the concrete member 10 than the connecting portions 30 and the horizontal reinforcing bars are embedded in the concrete to increase the effect of the synthesis of the connecting portions 30 and to increase the rigidity of the section changing portions, Which is characterized in that it can be efficiently controlled. The method according to claim 1,
The both ends of the horizontal reinforcing bars are connected to the vertical members on both sides and the center of the horizontal reinforcing bars extends further toward the center of the beam than the end of the web 33,
Wherein one end of the horizontal reinforcement is connected to the vertical member and the other end of the horizontal reinforcement extends further toward the center of the beam than the end of the web. 3. The method according to claim 1 or 2,
Wherein a lower long hole (37) passing through the web (33) is horizontally formed in a lower portion of the web of the web (33), and a stirrup reinforcing bar (70) is installed in the lower long hole (37) Bo. The method of claim 3,
An upper elongated hole 38 passing through the web 33 is formed horizontally on the upper side of the column 33 of the web 33 and a stirrup reinforcing bar 70 penetrates the upper elongated hole 38 to form a closed stirrup,
Wherein the stirrup reinforcing bar (70) penetrates the upper longitudinal hole (38), so that the stirrup reinforcing bar (70) does not protrude above the concrete in the interval of 300 mm to 500 mm from the end side of the column of the connecting portion (30) . 5. The method of claim 4,
The stirrup reinforcing bar (70)
A lower stirrup reinforcing bar (71) having a central portion penetrating the lower longitudinal hole (37) and bent at both ends thereof so as to extend over the upper cast steel rope (11); And
And an upper stirrup reinforcing bar (75) whose center portion passes through the upper elongated hole (38) and whose both ends are bent so as to span the upper casting stead (11)
The lower elongated reinforcing bar 71 is laid sideways and then inserted into the lower elongated hole 37 from one end of the lower stirrup reinforcing bar 71 and then inserted into the lower elongated reinforcing bar 71 vertically. Its horizontal length is longer than its height,
The upper elongated reinforcing bar 75 is laid sideways and then inserted into the upper elongated hole 38 from one end of the upper stirrup reinforcing bar 75 so that the upper elongated reinforcing bar 75 can be vertically erected. And the horizontal length thereof is longer than the height. 3. The method according to claim 1 or 2,
A lower groove 39 penetrating through the web 33 is horizontally formed in the lower portion of the opposite end of the web 33 at opposite ends of the web 33 and a stirrup reinforcing bar 90 penetrates through the lower groove 39 Steel composite concrete beams. The method of claim 3,
A lower groove 39 penetrating through the web 33 is horizontally formed at the lower end of the opposite end of the web 33 at opposite ends of the web 33 and a stirrup reinforcing bar 90 is installed through the lower groove 39,
In the section between the lower groove 39 and the lower long hole 37, stir bar reinforcing bars 80 are provided on both sides of the web,
Wherein one end of the stirrup reinforcing bar (80) is vertically bent to be closely attached to the side of the web, and the other end of the stirrup reinforcing bar (80) protrudes above the concrete.

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