KR101869458B1

KR101869458B1 - Composite box girder using steel beam and construction method therefor

Info

Publication number: KR101869458B1
Application number: KR1020170095480A
Authority: KR
Inventors: 김태균; 김영진
Original assignee: 김태균
Priority date: 2017-07-27
Filing date: 2017-07-27
Publication date: 2018-06-20

Abstract

The present invention relates to a composite box girder using a steel beam which can remarkably reduce the amount of steel used, effectively resist distortion and shearing force, and be manufactured and constructed at economic efficiency, and a construction method thereof. The composite box girder includes: steel beams of an I-shaped cross section spaced apart from each other to form an opening (S3) between upper and lower flanges, in which a horizontal width of the upper and lower flanges becomes an effective width (D2); a horizontal middle connecting member extending from the steel beams to connect middle portions of the steel beams; a vertical partition vertically extending from a bottom surface of the upper or lower flange of the steel beam, in which both sides are brought into contact with the middle portions, and the bottom surface is fixed to a top or bottom surface of the horizontal middle connecting portion; and compressed reinforcing concrete deposited in an space formed by the horizontal middle connecting member, the upper or lower flange and the vertical partition.

Description

Technical Field [0001] The present invention relates to a steel composite box girder using a steel beam,

The present invention relates to a steel composite box girder using a steel beam and a construction method thereof. More specifically, a steel composite box girder having an open-end steel composite box girder can remarkably reduce the amount of steel used and can effectively resist warping and shearing forces, thereby making it possible to efficiently and economically produce and construct steel composite box girders And a method of constructing the same.

Fig. 1A shows a conventional elevator type girder 10. Fig.

That is, the present invention provides a box-like steel composite girder which is less deformed by twisting without using a bracing material, enables stable bridge construction, maximizes the use efficiency of the steel material,

1A, the upper flange 13, the lower flange 11, and the pair of abdomen portions 12 are formed. The central portion in the longitudinal direction is formed with an opening S1 having an opened upper side, A girder forming step of forming a girder-shaped segmented steel girder whose upper end is closed to have a "ㅁ" shape in cross section;

A mold setting step of installing a mold for placing a partial bottom plate concrete for closing the opening portion in a central portion of the segmented steel girder with an open upper portion being supported on the bottom of the girder;

Placing a reinforcing bar so as to be embedded in the partial bottom plate and partially exposed to the outside of the partial bottom plate (14);

A partial bottom plate combining step of placing the un-hardened concrete in the formwork to synthesize the partial bottom plate 14 with the segmented steel girder to close the upper opening S1 of the U-shaped section; And removing the mold and the tile.

The upper end of the girder is closed so that the twist deformation is small without using the bracing material by using the gusset-shaped segmented steel girder 11 having a cross-section of "ㅁ" shape, and the partial bottom plate, which is a reinforced concrete, Thus maximizing the use efficiency of the steel.

However, additional girders and formwork are required inside the girder girder for forming the partial girder 14, and the amount of vertical and vertical stiffeners installed to reinforce the girder section of the girder girder 15 40%) was not significantly reduced.

FIG. 1B shows another conventional steel box girder 20.

A lower flange portion 21 in the form of a panel; A panel-shaped abdomen (22) longitudinally provided on both side portions of the lower flange portion (21); An upper flange portion 23 in the form of a panel provided to connect the abdomen portions 22 located opposite to each other; And a reinforcing concrete 25 integrally cured and having the same length as the top surface of the lower flange portion 21. The reinforcing concrete 25 is formed of a perforated type, ; &Lt; / RTI >

That is, the steel box girder is formed into a closed cross-section and the inner lower space S2 is synthesized with the reinforced concrete 11. When the lateral width of the upper and lower flanges becomes larger, the advance width by the SHEAR LAG The amount of steel required for the upper and lower flange fabrication is too much, which is inefficient, and it is difficult to solve the problem of pore generation occurring when the reinforced concrete is poured.

1C shows a cross-sectional view of a conventional I-type concrete filler girder 30. FIG.

That is, the I-type girders constituted by the two upper flanges 1, the abdomen 2 and the lower flange 3 are coupled to each other in the lateral direction so that the concrete portion 4 is filled in the space portion S21.

At this time, it can be seen that the horizontal plate 5 is connected between the abdominal region 2.

Therefore, when the width of the upper and lower flanges is increased, the effective width due to the shearing delay becomes smaller. However, when the two I-type girders As it is.

Korean Patent No. 10-1024827 (Title of the invention: Method of making box-shaped steel composite girder and method of constructing box-shaped bridge using the same, public date: March 31, 2011) Korean Patent No. 10-1182680 (Name of the invention: I type concrete filler girder, girder bridge using the same, production and construction method thereof, public date: September 14, 2012) Korean Patent No. 10-1634313, entitled "Steel Box Girders with Increased Sectional Stiffness and Moment Resistance and Method for Construction of Bridges Using the Same", publication date: June 30, 2016) Korean Patent No. 10-1022853 (Title of invention: Synthetic girders for use in bridges, published on Mar. 17, 2011)

The present invention relates to a steel composite box using a steel beam and a method of constructing the steel composite box, which are produced by synthesizing concrete and a steel beam, and the width of the upper and lower flanges in the transverse direction becomes longer It is possible to effectively solve the problem of inefficiently increasing the amount of steel to be used, to effectively resist torsional stiffness and shear force, to solve the problem of pore generation in the concrete synthesis, and to eliminate the use of a reinforcing material, The present invention provides a steel composite beam girder which can reduce the amount of steel material used for steel composite beams.

A steel composite box girder using a steel beam according to the present invention and a method of constructing the steel composite box girder using the steel beam according to the present invention is a steel composite box girder using a steel beam formed by an open box cross section between upper flanges and lower flanges, Both steel beams having I-shaped cross sections spaced apart from each other so as to form openings S3 in the lateral direction and formed in the effective width D2 due to the front end delay; And connecting the abdomen portions of the two steel beams to each other at a position spaced apart from the upper flange or the lower flange at portions where compressive forces act on the basis of the neutral axis when the bending moment acts, A horizontal abdominal connecting member formed to be able to move in the vertical direction A vertical partition wall extending vertically from the upper flange or the lower flange bottom surface of the steel beam so that both sides thereof contact the abdomen while the bottom surface is fixed to the upper surface or the lower surface of the horizontal abdomen coupling member; Reinforced concrete poured into an inner space formed by the horizontal abdomen connecting member, the upper flange or the lower flange and the vertical partition wall, and the thickness of the compressive reinforced concrete is increased so that the compressive force due to the moment increases .

According to the steel composite box girder using the steel beam according to the present invention and the construction method thereof, it is possible to secure the resistance against torsional rigidity and shear force, but also advantageous in limiting the advance due to shear delay, It is possible to provide a steel composite box using an economical steel beam and a construction method thereof.

Figs. 1A, 1B and 1C are perspective views of a conventional box-type steel composite girder,
2 is a structural perspective view of a steel composite box girder using a steel beam according to the present invention,
Fig. 3A, Fig. 3B, Fig. 3C and Fig. 3D Fig. 3C is a structural perspective view of a steel composite box girder using a steel beam according to the present invention,
4A, 4B and 4C are construction drawings of a steel composite box girder using a steel beam according to the present invention,
5A and 5B show a steel composite box girder using a steel beam of a simple bridge and a continuous bridge, and a construction method thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

[Steel composite box girder (100) using steel beam of the present invention]

FIG. 2 is a perspective view of a steel composite box girder using a steel beam according to the present invention, FIG. 3 is a perspective view of a steel composite box girder structure using a steel beam according to the present invention, FIG.

First, a steel composite box girder 100 using a steel beam according to the present invention is formed by forming a steel box girder with an open box cross-section in which an interval between upper flanges and a lower flange is not closed, Machined, welded, or joined together using H-shaped steel.

The steel composite box girder 100 using the steel beam beam includes a pair of steel beams 110 and 120, a horizontal stiffener 130, a vertical partition wall 140 and a compression reinforced concrete 150 as shown in FIG. 2 .

It can be seen that the pair of steel beams 110 and 120 are composed of the upper flanges 111 and 121, the abdomen portions 112 and 122 and the lower flanges 113 and 123 as a steel beam having an I-shaped cross section. , It is acceptable to use an existing H-shaped steel product.

If the upper and lower flange side surfaces of the steel beam are joined together by welding or the like as before, the entire length of the lateral width of the upper and lower flanges of each of the steel beams is not recognized as the effective width, The total length of the transverse width becomes smaller than the total length of the transverse width, which unnecessarily increases the amount of steel beam used.

In the present invention, the steel beams 110 and 120 are spaced apart from each other in the transverse direction so that each steel beam has an effective width D2 due to a front-end delay based on the connecting portion between the abdomen and the upper and lower flanges, (D1 = 2 * D2), so that a pair of steel beams are constrained to each other.

The horizontal abdominal connector 130 is used to restrain the respective steel beams 110 and 120 from each other.

The horizontal abdomen coupling member 130 is formed as a coupling member horizontally positioned between the pair of steel beam belts 112 and 122 and extending in the longitudinal direction of the steel beam so as to connect the two abdomen portions in the lateral direction.

The pair of steel beams 110 and 120 are coupled to each other in the transverse direction by the horizontal abdomen connecting member 130 and the forming position is determined depending on the bending moment acting on the steel composite box girder 100 according to the present invention, And is formed in the form of a horizontal plate or the like between the abdomen and away from the lower flange.

As shown in FIG. 3, the horizontal abdomen coupling member 130 may be a steel plate, a bended steel plate, or the like. The horizontal abdomen coupling member 130 may have a bending moment of a length extending in the longitudinal direction of the steel beam at a position spaced apart from the upper flange or the lower flange The upper and lower separation distance can be changed according to the size.

For example, in a simple beam, the steel composite box girder 100 has the largest bending moment (+ M) at the center portion of the steel composite box girder when it is mounted at both end portions. Therefore, The horizontal abdomen connecting member 130 may be formed so that the distance from the bottom of the upper flange decreases.

It is preferable that the horizontal abdomen connecting member 130 is formed to be formed in a step-like shape, a curved shape, a bent shape or the like in the manufacturing process.

As a result, it can be seen that the horizontal abdomen connecting member 130 is formed in such a manner that the abdomen is connected to the upper flange or the lower flange at a position where the compressive force acts on the basis of the neutral axis when the bending moment acts.

The vertical partition wall 140 effectively resists the twisting rigidity of the steel composite box girder 100 according to the present invention by abdominal connection between the pair of steel beams 110 and 120 and the horizontal abdomen coupling member 130, 150).

That is, as shown in FIG. 2, even though a pair of steel beams 110 and 120 and a horizontal abdomen connecting member 130 alone behave as a pair of steel beams, they are very vulnerable to warping.

In particular, it is necessary to compensate for the distortion when the steel girder of the curved girder is installed or when the bottom plate concrete is cast.

The vertical barrier 140 is vertically extended from the bottom of the upper flange or the lower flange so that both sides of the vertical flange are in contact with the abdomen and the bottom of the horizontal abdomen coupling member 130 is fixed to the upper surface of the horizontal abdomen coupling member 130, So that the rigidity of the steel composite box girder 100 can be secured,

The vertical partition wall 140 serves to close the discontinuity according to the distance from the upper and lower flanges along the extending direction of the horizontal abdomen coupling member 130 and to prevent the compression reinforced concrete from being damaged by the upper and lower flanges and the horizontal abdomen coupling member 130 It also acts as a finishing form when it is poured into a space by

Further, the horizontal abdomen coupling member 130 and the vertical partition wall 140 of the present invention serve as stiffeners (longitudinal and horizontal stiffeners, longitudinal stiffeners) for preventing distortion and buckling in the conventional box-type steel box girders. Since the steel composite box girder 100 does not use a conventional reinforcing material, the amount of steel used is drastically reduced, and the thickness of the horizontal abdomen connecting member 130 and the vertical partition wall 140 is determined by considering the bending moment, twist, buckling, .

The compressive reinforced concrete 150 is a concrete poured into a space formed by the upper and lower flanges, the horizontal abdomen coupling member 130 and the vertical partition wall 140. In the present invention, in particular, the lateral spacing between the pair of steel beam upper flanges The openings S3 formed in the openings can be used.

Therefore, unlike the conventional method, there is hardly any difficulty of pouring and filling, and it is preferable that air bubbles are discharged through the grooved grooves 141 at the corners of the vertical partitions.

It is preferable to use a stud so that the compression-reinforced concrete 150 can be integrally combined with the upper and lower flanges, the horizontal stiffener 130 and the vertical partition 140, Shear stress generates shear stress, where shear stress (τ = V * Q / I * b)

Where I is the shear stress (MPa), V is the shear force (kN), Q is the primary moment of inertia (mm3), I is the secondary moment of inertia (mm4)

In the above equation, when the value of the moment of inertia (I) increases, the shear stress becomes small. Therefore, it can be seen that the horizontal abdomen coupling member 130 and the compression-reinforced concrete 150 placed thereon with respect to the neutral axis are very effective in resistance to the shear force as the distance from the neutral axis N.A increases.

Since the compression-reinforced concrete 150 functions to fill the spaces formed by the upper and lower flanges, the horizontal abdomen coupling member 130 and the vertical partition walls 140, the buckling of the steel composite box girder 100 together with the vertical partition walls 140 It is possible to eliminate or minimize the longitudinal stiffener and the horizontal stiffener.

FIG. 3 is a cross-sectional view of the horizontal abdominal connector 130 of the present invention.

For example, the horizontal abdomen connecting member 130 is formed in the form of a horizontal plate or a bent plate,

As shown in FIG. 3A, it can be seen that the compression-reinforced concrete 150 can be formed in the form of a horizontal plate, and the compression-reinforced concrete can be formed in the vertical partition 140 to prevent voids from being formed by grooving. As shown in FIG. 3B, the upper reinforcing concrete 150 may be formed in the form of an upwardly curved arch plate, and the vertical partition wall 140 may be formed with compression-reinforced concrete 3C, the compression-reinforced concrete 150 may be installed in the form of a bent or curved plate material horizontally or inclined upwardly, and the vertical partition 140 may have a vertical partition 140, It can be seen that the compression-reinforced concrete can be formed so as to prevent the occurrence of pores due to the grooving. As shown in FIG. 3D, the compression-reinforced concrete 150 And the vertical partition wall 140 can be formed with a compression-strengthened concrete so as not to generate a gap due to grooving.

FIG. 4 is a view showing a construction of a steel composite box girder 100 using a steel beam according to the present invention. As shown in FIG. 4, according to the bending moments acting on the steel composite box girder 100, The formation positions of the partition wall 140 and the compression-reinforced concrete 150 can be confirmed.

4A, a momentum (-M) is generated in a bridge section L2 of a steel composite box girder 100 using a steel beam, and a center moment L1 + M) is generated.

The section height of the pierced portion (L2) compression-strengthened concrete (150) at which the momentum (-M) is generated is formed to be larger in the receiving portion than in the other portions except for the bridge portion and below the lower flange position of the steel beam This can be said to be the case where the steel composite box girder 100 having a very high sectional rigidity is placed at the bridge portion in the continuous bridge.

The bridge portion L2 at which the momentum (-M) is generated is spaced apart from the lower flange of the steel beam, or the horizontal abdomen coupling member 130 and the plurality of vertical partition walls 140 connected to the lower flange are calculated in the structural calculation Reinforced concrete 150 is formed in a state where it is installed in accordance with the spacing distance, and the horizontal abdomen coupling member 130 is formed in the form of a horizontal plate, and the compressive reinforced concrete is connected to the horizontal abdomen coupling member 130 It may be installed through the preformed opening S3.

The distance between the upper flange of the steel beam and the horizontal abdomen coupling member 130 is the largest in the middle portion L1 where the positive moment is generated and the smaller the moment is, Reinforced concrete 150 is formed in a stepped manner in which the spacing distance of the connecting member 130 is reduced and a vertical partition 140 is formed at a portion where the spacing distance is changed, (S3), and the vertical partition wall 140 is also used as a finish form of the compression-strengthened concrete (150).

Next, referring to FIG. 4B, a momentum (-M) is generated also in the bridge section L2 of the steel composite box girder 100 using the steel beam, and the center section (L1) (+ M) occurs. The difference from FIG. 4A is that there is no difference in height between the cross-sectional height of the steel composite box girder 100 at the bridge portion and the cross-sectional height of the longitudinal section.

It can be seen that the cross-sectional height of the pierced portion (L2) compression-strengthened concrete (150) at which the momentum (-M) is generated is formed at the lower flange position of the steel beam more largely This is a case where the steel composite box girder 100 having a very high section rigidity is placed on the bridge portion in the continuous bridge.

The bridge portion L2 at which the momentum (-M) is generated is spaced apart from the lower flange of the steel beam, or the horizontal abdomen coupling member 130 and the plurality of vertical partition walls 140 connected to the lower flange are calculated in the structural calculation The cross-sectional height of the compression-strengthened concrete 150 and the height of the vertical partition wall 140 are lowered stepwise as the momentum (-M) decreases in both alternating directions from the bridge pier, and the compressive strength of the compressive reinforced concrete 150 are inserted through the opening S3 previously formed in the horizontal abdomen connecting member 130 and the vertical partition wall 140 is also used as a finishing form of the compressive reinforced concrete 150. [

As shown in FIG. 4C, when the slab 300 is integrally formed on the upper flange of the steel composite box girder 100 using the steel beam, the steel composite box girder 100 and the bottom plate 300, It can be seen that the compression-reinforced concrete 150 can be pre-installed through the opening S3 when the bottom plate concrete is poured.

[Steel composite box girder construction method using steel beam]

FIG. 5A shows a steel composite box girder using a steel beam of simple cross-section and a construction method thereof, and FIG. 5B shows a steel composite box girder using a continuous steel beam and its construction method.

5a, the two alternations 200 are firstly constructed as the bridge substructure, and the steel composite box girder 100 using the steel beam according to the present invention is first installed such that both ends of the steel composite box girder 100 are mounted on the upper surfaces of the two alternating 200 .

In the steel composite box girder 100 using the steel beam, since the center portion L1 is formed with a positive moment (+ M) after the mounting and the bottom plate construction, the center portion of the steel composite box girder 100 is separated from the upper flange The horizontal abdomen connecting member 130 having the greatest distance is formed and the spacing distance becomes smaller as it goes to both ends in a stepwise manner. A plurality of vertical barriers 140 are formed in a part where the separation distance varies according to the calculation of the structure, Reinforced concrete 150 is formed by the vertical partition wall 140 which forms the compression-strengthened concrete pipe 150.

Also, a plurality of steel composite box girders 100 using a steel beam can be mounted in a direction perpendicular to the throttling axis, and they can be connected to each other using a beam.

After a plurality of steel composite box girders 100 having steel beams are mounted on the two alternations 200 as the bridge substructure, the bottom plate concrete is placed on the upper flange of the steel composite box girder, So that the slab 300 can be synthesized and completed to complete the bridge.

5b, the bridges 210 between the two alternations 200 and the alternations 210 are first constructed as the bridge substructure, and the steel composite box girder 100 using the steel beam of the present invention is installed in both alternations 200, And the pier 210 are mounted on the upper surface of the pier 210 in such a manner that both ends thereof are mounted.

At this time, the pier portion L2 of the steel composite box girder 100 using the steel beam is supported, and the height of the section of the bridge portion L2 is larger than the section height of the section of the center portion L1. .

As a result, the momentum (-M) is generated at the pier portion (L2) where the pier is installed, and the moment (+ M) occurs at the central portion (L1) between the pier and the pier. The bridge portion L2, at which the moment M- is generated,

A horizontal abdominal connector 130 spaced from the lower flange or connected directly to the lower flange,

Reinforced concrete 150 is formed in a state where a plurality of vertical partitions 140 are installed according to a distance calculated in the structural calculation, the horizontal abdomen connecting member 130 is formed in a horizontal plate shape, The reinforced concrete is poured through the opening S3 previously formed in the horizontal abdomen connecting member 130.

In addition, in the section where the longitudinal moment (+ M) of the central section (L1) is large, the distance between the horizontal flange and the vertical flange of the steel beam is the largest, The vertical partition wall 140 is formed at a portion where the separation distance is changed and the compression-reinforced concrete 150 is formed by a pair of steel plates It can be seen that it is poured into the opening S3 of the beam to be formed inside.

A plurality of steel composite box girders 100 using steel beams may be mounted in a direction perpendicular to the throttling axis, and they may be connected to each other using a beam.

After a plurality of steel composite box girders 100, which are steel beams, are continuously installed on the two alternating sections 200 and the bridge piers 210, the bottom plate concrete is placed on the upper flange of the steel composite box girder. It is possible to complete the bridge by synthesizing and constructing the slabs 300 by using the illustrated formwork and tall building.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning, scope and equivalence of the claims are to be construed as being included within the scope of the present invention do.

100: Steel composite box girder 110, 120: Steel beam
130: horizontal abdomen connecting member 140: vertical partition wall
141: grooving 150: compression-reinforced concrete
200: shift 210: pier
300: Slab

Claims

A steel composite box girder (100) using a steel beam formed by an open box cross section between the upper flanges and the lower flange,
The two steel beams 110, 120 of I-shaped cross section spaced apart from each other so as to form an opening S3 between the upper and lower flanges so that the lateral width of the upper and lower flanges is formed by the effective width D2 by the front end delay;
And a bending moment generating unit for generating a bending moment at a position spaced apart from the upper flange or the lower flange at a portion where a compressive force acts on the basis of the neutral axis when the bending moment acts, A horizontal abdomen connecting member 130 formed to connect the upper and lower ends of the main body 100 to each other;
A vertical partition wall 140 formed to be vertically extended from the upper flange or the lower flange bottom of the steel beam so as to be fixed to the upper or lower surface of the horizontal abdomen coupling member 130 while the both sides thereof contact the abdomen; And
Reinforced concrete 150 poured into the inner space formed by the horizontal abdomen coupling member 130, the upper flange or the lower flange and the vertical partition wall 140,
Wherein the thickness of the compression-reinforced concrete (150) is formed to increase together with a compression force due to a moment.

The method according to claim 1,
The two steel beams 110,
The horizontal abdominal connector 130 is formed between the upper flange and the lower flange so as to be spaced apart from the upper flange or the lower flange in a state where the steel beams of the I-shaped cross section formed by the upper flange, the abdomen and the lower flange are laterally spaced from each other, Reinforced concrete (150) is filled with the opening (S3) through the opening (S3), and the reinforcing concrete (150) is filled through the opening (S3).

The method according to claim 1,
The horizontal abdomen coupling member 130 is formed in a horizontal plate, a bent plate, or an arcuate shape to connect the abdomen portions of both steel beams to each other.

The method according to claim 1,
The vertical barrier ribs 140
The function of finishing the discontinuous portion A in which the thickness of the compressive reinforced concrete is varied according to the distance from the upper and lower flanges in accordance with the extending direction of the horizontal abdomen coupling member 130 and the function of compressively reinforcing the concrete, A steel composite box girder using a steel beam that acts as a finishing die when it is poured into a space formed by the steel frame 130.

The method according to claim 1,
The compression reinforced concrete (150) is formed such that the thickness of the compressive reinforced concrete (150) varies according to the size of the compressive force applied by the longitudinal or momentum relative to the neutral axis of the steel composite box girder.

(a) constructing two alternations;
(b) placing the steel composite box girder (100) using the steel beam of claim 1 between the two alternations, wherein the compression reinforced concrete (150) of the steel composite box girder (100) ) Is a method of constructing a steel composite box girder using a steel beam formed to have a thickness different according to the magnitude of the compressive force due to the longitudinal force based on the neutral axis of the steel composite box girder.

(a) constructing alternating turns and piers;
(b) compressing the steel composite box girder (100) using the steel beam so that the steel composite box girder (100) using the steel beam as set forth in claim 1 is interposed between the two alternations and via a pier; The reinforced concrete (150) is a steel composite box girder construction method using a steel beam formed so as to have a different thickness depending on the magnitude of compressive force due to the longitudinal and longitudinal moments based on the neutral axis of the steel composite box girder.

8. The method according to claim 6 or 7,
The steel composite box girder construction method according to claim 1, wherein the step (b) further comprises the step of integrally forming a slab on the upper surface of the steel composite box girder (100) using the steel beam.