KR101678999B1 - Method of manufacturing composite girder and of constructing birdge upper structure using same - Google Patents

Abstract

The present invention relates to a steel composite girder and a method of constructing a bridge overhead structure using the steel composite girder, wherein the center portion is formed in a cross-sectional shape formed by the abdomen portion and the lower flange portion and the end portion is formed by the upper flange and the lower flange, A steel girder fabricating step of fabricating a steel girder having an I-shaped cross-section; A step of installing a front end connection member protruding upward on the upper flange; A mold setting step of installing a mold surrounding the upper portion of the abdomen of the steel girder and the upper flange; A concrete synthesizing step of placing the unhardened concrete in the mold so that the upper end of the shear connector is protruded from the upper surface of the casing concrete to synthesize casing concrete in the steel girder to form a steel composite girder; A die removing step of removing the die; A steel composite girder which can prevent cracking of the casing concrete from cracking and improve the sectional efficiency and to make the synthesis of the steel composite girder and the bottom plate concrete more robust and a bridge superstructure using the same Provides a construction method.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a steel composite girder and a method of constructing a bridge superstructure using the steel composite girder manufactured by the method. ≪ Desc / Clms Page number 1 >

The present invention relates to a steel composite girder and a method of constructing a bridge superstructure using the steel composite girder. More specifically, the present invention relates to a steel composite girder which improves cross-sectional efficiency while preventing splitting cracks from being generated in casing concrete, The present invention relates to a method for manufacturing a steel composite girder which can make the synthesis of a steel composite girder and a bottom plate concrete more robust and a construction method of a bridge upper structure using the steel composite girder manufactured thereby.

Generally, steel can resist effectively tensile force, but there is a problem that buckling occurs in compressive force, causing sudden collapse. Concrete can resist effectively compressive force, but is vulnerable to tensile force. There is a problem that the load-bearing capacity of the structure is rapidly reduced.

1A, a steel composite girder 1 having a structure that resists with casing concrete 20 and resists with a steel material 10 at the lower edge of a neutral axis where a tensile force is applied is fabricated , Are used as structural members of bridges.

However, since the neutral stiffness of the steel composite girder 1 is supported by the casing concrete 20 instead of the steel material 10 because compressive stress predominantly acts on the steel reinforced concrete girder 1, the abdomen portion 10b and the lower flange Cracks 88 are generated in the casing concrete 20 on the upper side of the upper end portion of the abdomen portion 10b when the casing concrete 20 is combined with the steel girder 10 to which the cross- do.

In order to prevent splitting cracks, the upper end portion of the abdomen of the steel girder is formed into a puzzle-strip shape (10x) formed by a bent portion and a concave portion, and a reinforcing bar 25 surrounding the inside of the casing concrete 20 is formed on the steel girder 10 And the upper end of the casing concrete 20, there is still a limitation in that splitting cracks are generated in the case of the point portion (girder end portion) where the shear force is large. In addition, a method of increasing the abdomen thickness to increase the resistance to shear force can be sought, but this increases the amount of unnecessary steel material, which causes a problem that the sectional efficiency is lowered.

Meanwhile, in order to firmly synthesize the bottom plate concrete 30 and the steel composite girder 1 in the process of constructing the upper structure of the bridge using the steel composite girder 1 constructed as described above, A shear connection member (not shown) for assisting the shear reinforcing bars 25 (Fig. 2) to be densely arranged inside the casing concrete 20 at the fulcrum portion and for assisting the composite of the steel girder 10 and the casing concrete 20 It should be installed. The casing concrete 20 of the steel composite girder 1 and the bottom plate concrete 30 synthesized on the upper side are integrally formed by the shear reinforcing bars 25 integrally with each other .

However, in the process of manufacturing the steel composite girder 1, the process of densely installing the shear reinforcing bars 25 projected outward is very troublesome and difficult in itself, wasting materials, It is a cause of delaying the installation, installation and curing of the formwork for synthesizing the casing concrete 20 after the shear reinforcing bars 25 are laid. Nevertheless, since the shear reinforcement 25 is embedded in the casing concrete 20 rather than being coupled to the rigid steel girder 10, the shear force acting between the casing concrete 20 and the bottom plate concrete 30 Vulnerable problems also arise.

Therefore, there is a desperate need for a method capable of forming a solid enough to withstand the shear force acting between the steel composite girder 1 and the bottom plate concrete 30.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a composite concrete girder which can prevent cracking in a casing concrete synthesized to enclose a part of a steel girder, And a method for constructing a bridge overhead structure using the steel composite girder manufactured by the method.

Particularly, the present invention is intended to make it possible to withstand a shearing force acting largely at the fulcrum portion of the steel pipe compared to the central portion with a sufficient amount of steel material, thereby improving the sectional efficiency and obtaining economical efficiency.

Also, according to the present invention, a steel girder, a casing concrete and a bottom plate concrete are connected at once by a shear connector to a steel girder, a casing concrete, and a bottom plate concrete To be more firmly synthesized.

In addition, the present invention prevents the introduction of compressive stress due to the self weight of the composite girder into the casing concrete during the manufacturing process, and introduces a tensile stress to cancel the compressive stress acting on the upper side of the steel girder in advance, And the like.

In addition, in the present invention, the casing concrete is synthesized on the neutral axis of the girder while the steel girder is supported in the minbore type, and the tensile stress generated at the lower edge of the center of the girder is compensated by the compression prestress introduced at the lower edge of the center of the girder And at the same time introduces tensile stress in advance to the upper part of the steel girder of the steel composite girder so as to cancel the compressive stress acting on the joint in advance to realize a higher load carrying capacity.

In the construction of the upper structure of the continuous bridge, it is possible to effectively support the tensile stress largely acting on the neutral axis upstanding at the continuous point portion and the compressive stress largely acting at the neutral axis lower edge, To achieve safety and economy at the same time.

SUMMARY OF THE INVENTION The present invention has been achieved in order to solve the above problems, and has as its object to provide an apparatus and a method for controlling the operation of the apparatus. The apparatus includes an upper flange and a lower flange, A steel girder fabricating step of fabricating a steel girder formed in a shape of a " A step of installing a front end connection member protruding upward on the upper flange; A mold setting step of installing a mold surrounding the upper portion of the abdomen of the steel girder and the upper flange; A concrete synthesizing step of placing the unhardened concrete in the mold so that the upper end of the shear connector is protruded from the upper surface of the casing concrete to synthesize casing concrete in the steel girder to form a steel composite girder; A die removing step of removing the die; The present invention also provides a method of manufacturing a composite steel girder.

This makes it possible to ensure a sufficient rigidity by using a casing concrete effective for supporting a compressive force as a compression member and a steel material effective for supporting a tensile force as a tensile member. The end of the steel girder is formed into an I- In addition to being able to withstand the shear force, the central portion of the steel girder is formed as a cross section having no upper flange, so that the low cross sectional force is resisted with a small amount of steel material usage, And to maximize economic efficiency.

Accordingly, not only the effect of reducing the sectional rigidity due to the buckling caused by the use of the steel material as the compression member can be prevented in advance, but also the structural stability can be maintained without installing additional reinforcement to prevent buckling.

In addition, in the end portion of the girder where the shear force acts largely, the upper flange and the lower flange are respectively formed in an I-shaped cross section at the upper and lower ends of the abdomen, so that cracks in the casing concrete, which is synthesized on the steel girder, So that the conventional problems in which the load-carrying capacity is lowered can be solved.

In addition, when a continuous bridge connecting the girder in the longitudinal direction at the fulcrum portion is constructed by using the steel composite girder manufactured as described above, the bending moment largely acting on the neutral axis upstanding portion at the continuous fulcrum portion is formed as the upper flange It is possible to obtain an advantageous effect that the efficiency of the material is further improved.

The upper end of the shear connection member may be formed to protrude from the upper surface of the casing concrete. Accordingly, even when the casing concrete is synthesized on the steel girder, the shear connection member coupled to the upper flange protrudes outwardly. Therefore, during the process of constructing the bridge using the manufactured steel composite girder, The shear connection material is directly bonded to the bottom plate concrete of the bridge, so that the coupling between the casing concrete of the composite composite girder and the bottom plate concrete is more robust. Therefore, even if a large shear force acts between the steel composite girder and the bottom plate concrete, it is possible to obtain stable integrated behavior by maintaining the composite state with the bottom plate concrete by the shear connection material fixed to the steel material. In addition, even if shear reinforcing bars are not separately installed in the casing concrete of the steel composite girder or less than the conventional steel reinforced concrete girder, it is possible to combine the steel girder, the casing concrete and the bottom plate concrete by the shear connection material at one time, , It is possible to realize a structure system which is more inexpensive and a rigid structure of the girder and the bottom plate can be realized and the construction period can be shortened.

According to an embodiment of the present invention, the steel girder is simply supported at a support point of L / 2 to L / 4 (where L is the length of the steel girder) A steel girder supporting step for supporting the steel girder; A supporting point moving step of moving the supporting point so that the steel girder is supported at both ends after the die removing step; And the like.

In this way, the casing concrete is synthesized on the neutral axis of the girder under the condition that the steel girder is supported in the mining type, and compressive prestress is introduced into the lower part of the middle part of the steel girder due to the self weight of the inside portion of the steel girder and the self weight of the casing concrete. The support prism of the girder is moved to both ends of the girder in the same manner as the support of the girder so that the compressive prestress introduced into the lower edge of the center of the steel composite girder due to the weight of the steel girder and the weight of the casing concrete, And by introducing tensile stress in advance to the upper part of the steel girder of the composite girder at the same time, the bottom plate concrete is synthesized on the upper side of the steel composite girder and the compressive stress acting during the live load application It is possible to obtain an advantage that it can be canceled in advance.

The mold installation step according to the present invention may be installed in a state where the formwork is supported on the floor, but it may be installed to be supported by the steel girder. This makes it possible to prevent the compressive stress due to the weight of the casing concrete from being introduced into the casing concrete by making the weight of the casing concrete synthesized in the steel girder supported by the steel girder.

Furthermore, when the casing is installed in a state in which the formwork is supported by the steel girder and at the same time the casing concrete is synthesized in the mining condition of the steel girder, the compressive stress due to its own weight is prevented from being introduced into the casing concrete, It is possible to obtain an advantageous effect that a higher load carrying capacity can be realized by previously introducing a tensile stress canceling the compressive stress acting on the joint.

Introducing a temporary concentrated load downward at both ends of the steel girder after the step of supporting the steel girder; After the concrete synthesis step, removing the temporary concentrated load; It is possible to control the amount of tensile prestress introduced into the steel of the compression prestress and the neutral axis upstream introduced into the neutral axis of the steel composite girder by the temporary concentrated load in addition to the deflection effect due to self weight in the mining condition have.

On the other hand, an end portion of the steel girder having an I-shaped cross section has a length of 0.05L to 0.33L of the steel composite girder length (L). Specifically, in the case of a simple bridge in which a steel composite girder is simply supported, by setting the length of the end portion at 1/20 times or more of the total length (L) of the steel composite girder, splitting cracks It can not withstand. Further, in the case where the steel composite girder is a continuous joint connected in the longitudinal direction on a continuous support point (for example, at the upper side of the pier), a tensile stress acts on the neutral axis at the end of the girder located above the continuous point portion, In order to be able to withstand this, the end of the I-shaped cross section which can withstand the tensile stress on the neutral axis up to a length equal to 1/3 times the total length L of the girder, Is formed. As described above, by forming the I-shaped cross section which can withstand a high sectional force on the neutral axis upstanding only in a section where the moment and the shearing force act largely, the use efficiency of the steel is improved and the splitting crack can be reliably prevented .

At this time, in the middle portion where the cross section of the steel girder is formed in the shape of 'I' ', the cross section of the steel girder is formed higher than the end portion of the upper girder by the height of the upper flange, ; Preparing an upper flange having a longitudinal groove formed therein for receiving a top portion of the abdomen; Coupling the upper flange and the abdomen with the upper portion of the abdomen partially received in the groove of the upper flange; A steel composite girder may be manufactured.

As a result, the upper flange is joined to the end of the steel composite girder to form an I-shaped cross section, and the upper flange is not joined to the center of the girder, The upper flange and the abdomen remain firmly engaged with each other even when a high sectional force is applied to the upper flange and the abdomen, The advantage can be obtained.

Meanwhile, the method of constructing the composite composite girder according to the present invention may be such that the casing concrete is synthesized over the entire length of the steel girder, but the casing concrete is synthesized only for a part of the length of the steel girder. For this purpose, the formwork is formed so as not to wrap at least one of both ends of the steel girder, and the steel composite girder can be manufactured to have an end portion where the casing concrete is not combined.

Meanwhile, in the present invention, even when the upper structure of the bridge is constructed by using the steel composite girder manufactured as described above, the steel composite girder is manufactured so that the casing concrete is not synthesized at any one of the both ends, A girder mounting step for simply placing the girder on the lower structure of the bridge, wherein the end of the casing concrete not being combined is disposed on the continuous fulcrum part; A girder connecting step of connecting the steel composite girders arranged in the throttle direction across the continuous focal point portion by attaching a connecting steel plate to the upper flange and interconnecting them; A bottom plate composite step of placing the bottom plate concrete on the upper side of the steel composite girders and synthesizing the bottom plate concrete with the steel composite girder so that the connecting steel plate in the throttle direction of the steel composite girders is embedded by the bottom plate concrete ; The present invention also provides a method of constructing a bridge superstructure.

In this way, in the case where the end portion of the steel composite girder forms the continuous fulcrum portion, the steel composite girder without the casing concrete at the end portion is mounted on the bridge substructure forming the continuous focal point portion, The exposed upper flange of the girder end is welded or bolted to the connecting steel plate, and the steel girder at the continuous point portion is buried when the bottom plate concrete is laid, It is possible to support the tensile stress according to the tensile stress to the connecting steel plate as well as the compressive stress of the neutral axis under the continuous point portion simultaneously with the placement of the bottom plate concrete and the composite concrete being integrally synthesized . By such a construction method, the sectional force acting at the continuous point portion can be effectively canceled, and the construction period can also be shortened, so that the economical efficiency can be improved.

In addition, the cross section of the steel girder and the casing concrete with the upper flange formed at the continuous point portion together increases the section rigidity, thereby reducing the bending moment generated at the bottom portion, and the strength of the steel material And the upper flange are combined together, so that the effect of being able to effectively resist the moment generated by the fixed load and the live load can be obtained.

The term " undercarriage " of the bridges used in this specification and claims is used in the art to refer to the term " shift " or " bridge " The term "superstructure" is defined as a term used in the art to collectively mean "girder", "bottom plate", "railings" and the like, which are allowed to pass on the substructure of a bridge.

As described above, the present invention is characterized in that the end portion is formed in an I-shaped cross section in which the upper flange and the lower flange are respectively coupled to the upper and lower ends of the abdomen, and the middle portion is formed into a " Sectional shape and can endure the shear force acting largely at the end portion and can be supported by a small amount of steel material which acts at a low level in the central portion to minimize the amount of expensive steel material while improving the sectional efficiency and maximizing the economical efficiency The present invention also provides a method of manufacturing a composite steel girder.

Therefore, the present invention can solve the conventional problem that splitting cracks are generated in the casing concrete which is synthesized at the edge of the neutral axis of the steel girder at the end of the girder where the shear force largely acts.

In addition, since the shear connection member is formed to protrude from the upper flange of the end portion of the girder toward the outer side of the casing concrete, the composite of the steel girder and the casing concrete is further strengthened by the shear connection member, Since the composite of the composite girder and the bottom plate concrete is made more rigid, the steel composite girder and the casing concrete are integrally formed by the shear connection member coupled to the steel girder, as compared with the integration by the shear reinforcement, Effect can be obtained.

Further, since the bottom plate concrete and the steel composite girder are integrally synthesized, even if the shear reinforcement is not separately laid in the casing concrete of the steel composite girder or less than the conventional structure, the girder and the bottom plate are robust And the construction time can be shortened.

Further, since the height of the abdomen at the end portion of the upper composite flange is reduced by the height of the upper flange, even if the cross section of the composite girder is not constant over the girder length, the height of the composite girder becomes uniform as a whole, Can be prevented.

Further, according to the present invention, the steel composite girder is formed such that the upper flange and the abdomen are coupled to each other while the groove of the upper flange accommodates a part of the abdomen, so that the cross- So that they can stably and integrally behave as one structural member.

Further, in the construction of the continuous bridge connecting the steel composite girder in the longitudinal direction at the continuous point portion, the steel composite girder without the casing concrete is mounted on the continuous point portion at the end portion, When the flange is welded or bolted to the connecting steel plate, the steel girder of the continuous point portion is buried when the bottom plate concrete is poured, so that the momentum acting on the continuous point portion is effectively applied to the connecting steel plate The compressive stress of the neutral axis under the continuous point portion can be supported by the composite concrete that is integrally synthesized simultaneously with the placement of the bottom plate concrete and the construction period is shortened to improve the workability An advantageous effect can be obtained.

That is, according to the present invention, the bending moment largely acting on the neutral axis upstanding at the continuous point portion can be effectively canceled by the steel material of the upper flange of the end portion, the efficiency of the steel material can be further improved, the workability is improved, The combined structure of the steel composite girder and the bottom plate concrete can be advantageously used to realize a structural system which realizes a stable integral behavior.

Fig. 1A is a perspective view showing the appearance of a conventional steel composite girder,
1B is a cross-sectional view of FIG. 1,
Fig. 2 is a cross-sectional view of a composite structure of bottom plate concrete and steel composite girder of Fig.
FIG. 3A is an exploded perspective view of a composite steel girder according to an embodiment of the present invention, FIG.
FIG. 3B is an assembled perspective view of FIG. 3A,
FIG. 3C is a sectional view taken along the cutting line AA in FIG. 3B,
FIG. 3D is a sectional view taken along the cutting line BB in FIG. 3B,
4A to 4G are views showing a sequential construction according to a method of manufacturing a composite steel girder according to an embodiment of the present invention,
FIG. 5A is a sectional view taken along the cutting line CC in FIG. 4G,
FIG. 5B is a cross-sectional view taken along line DD of FIG. 4G,
FIG. 6A is a perspective view showing a structure of a steel composite girder fabricated according to a manufacturing method according to another embodiment of the present invention, FIG.
FIG. 6B is a sectional view taken along the cutting line FF in FIG. 6A,
FIG. 6C is a sectional view taken along the section line GG in FIG. 6A,
FIG. 6D is a sectional view taken along the line HH in FIG. 6A,
FIGS. 7A through 7C illustrate a sequential construction of a bridge overhead structure according to an embodiment of the present invention.

Hereinafter, a method for manufacturing a composite steel girder 100 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

As shown in the drawing, the steel composite girder 100 according to the embodiment of the present invention is characterized in that the central portion 110c is formed by joining the abdomen portion 112 and the lower flange 111 to form a " Is composed of a steel girder 110 formed by combining an abdomen portion 112 and upper and lower flanges 111 and 113 to form an I-shaped section and a casing concrete 120 combined with a neutral axis of the steel girder 110 And a shear connection member 114 fixed to the upper surface of the upper flange 113 and protruding from the upper surface of the casing concrete 120.

As shown in FIGS. 3A to 3D, the steel girder 110 is formed as a 'I' -shaped section at the center portion 110c and an I '-shaped section at the end portion 110e. According to another embodiment of the present invention, the abdomen 111 may be formed to have the same height over the entire length L of the girder. However, as shown in FIGS. 3A and 3B, the thickness t of the upper flange 113 A groove 113a is formed in the upper flange 113 for receiving the upper end portion of the step 112a of the abdomen 112. The groove 113a has a predetermined length s, So that a part of the upper end of the abdomen 112 is accommodated in the groove 113a. The length s of the groove 113a is preferably set to a length that is proportional to the length L of the girder and is set to a length sufficient to secure a firm connection between the upper flange 113 and the abdomen 112 . The upper flange 113 has an inclined surface 113s directed toward the center of the girder to minimize the abrupt change in the cross section of the 'ㅗ' shaped section and the 'I' shaped section.

The end portion 110e and the central portion 110c of the steel girder 110 are different from each other in sectional shape but the step 112a corresponding to the thickness t of the upper flange 113 is formed in the abdomen portion 112, Since it is formed at the same height (H) over the entire length (L), it is possible to eliminate the discontinuous points of the stress transmission for supporting the fixed load and the live load acting on the common, and can be utilized as a structural member in which the local stress is not concentrated .

Since the upper flange 113 of the steel girder is formed with the groove 113a to accommodate the upper end of the abdomen 112 and the upper flange 113 is coupled to the abdomen 112, The coupling length between the upper flange 113 and the abdomen 112 is maintained to be a firmly coupled state even when a high sectional force is applied, .

Here, the end portion 110e is defined as 0.05L to 0.33L of the girder length L. [ More specifically, when the steel composite girder 100 is used in a simple bridge, the length of the end portion 110e is set to be not less than 1/20 times the total length L of the steel composite girder, It is possible to sufficiently prevent cracking. And is set to about 1/20 to 1/5 of the girder length (L) for economical efficiency. On the other hand, when the steel composite girder 100 is used for continuous bridging, the region where the tensile stress acts on the neutral axis upper portion due to the influence of the momentum is long, so that the length of the end portion 110e is set to the entire length L), the use amount of the steel material is minimized to increase the sectional efficiency, and even splitting cracks of the casing concrete can be prevented even at a high sectional force acting largely at the fulcrum portion.

The casing concrete 120 may be composited on the neutral axis over the entire length of the steel girder 110 as shown in Fig. 4G and may be combined with the casing concrete 120 except for a part of the end of the steel girder 110 as shown in Fig. And may be synthesized in the neutral axis.

The shear connection member 114 is formed at a higher height 114h than the conventional shear connection member 114 so that the casing concrete 120 surrounds a portion of the abdomen 112 and the upper flange 113, Even if it is synthesized in the casing concrete 120, it is protruded to the outside of the upper surface of the casing concrete 120. Here, the protruding height of the front end coupling member 114 protruding from the upper surface of the casing concrete 120 is sufficient to assist sufficient coupling with the bottom plate concrete 105 synthesized on the steel composite girder 100 during the construction of the bridge And is determined to be smaller than the thickness of the bottom plate concrete 105.

The steel composite girder 100 according to the present invention having the above-described structure has the end portion 110e formed in an I-shaped section so as to withstand a high shearing force acting on the bridge portion, and the central portion 110c is formed into a cross- And the compressive stress acting dominantly on the neutral axis is supported by the casing concrete to maximize the sectional efficiency and maximize the economical efficiency while minimizing the amount of the expensive steel material and to be combined with the steel girder at the bridge point portion where the shear force acts largely It is possible to solve the problem of splitting cracks occurring in the casing concrete.

Hereinafter, a method of manufacturing the composite steel girder 100 according to the present invention will be described in detail.

Step 1: As Figures 3a shown in Figure 3d, the central part (110c) is formed in a 'ㅗ "shaped cross section formed in the abdomen 112 and the lower flange 111, the end portion (110e) is the upper flange ( 113 and the lower flange 111 are connected to each other by the abdomen portion 112. [

Here, the lower flange 111, the abdomen 112, and the upper flange 113 may be joined by various known means, for example welded. If the steel girder 110 to be manufactured is to be used for simple bridging, the end portion 110e is determined to be 1/20 to 1/5 of the total length L of the girder, and the steel girder 110 to be manufactured is continuous The end portion 110e is set to be 1/5 to 1/3 of the total length L of the girder.

At this time, it is preferable that the step 112a shown in FIG. 3A is formed on the abdomen portion 112 so that the overall height H of the steel girder 110 is made constant, but the present invention is not limited to this.

The upper end of the upper flange 113 of the manufactured steel girder 110 is formed with a shear connection member 114 longer than the thickness of the casing concrete 120 synthesized at a later stage, It is fixed with a length shorter than the combined thickness of the thickness of the concrete 105 and the thickness of the casing concrete 120. [

Step 2 : The position of the support point 55 is moved (66) to the center of the steel girder 110 as shown in FIG. 4A with respect to the steel girder 110 manufactured in step 1. At this time, the position of the fulcrum 55 becomes a position separated by L / 4 to L / 2 from the end. However, if the distance Li between the support points 55 is small, the steel girder 110 is placed in an unstable state. Therefore, the steel girder 110 may be provided with a separate means for maintaining a stable posture, .

As a result, the ends of the steel girder 110 are mounted in the form of bolts, and the center portion of the steel girder 110 is convex upward and sided at both ends by its own weight.

Step 3 : Depending on the case, a temporary concentrated load Fa may be applied to both ends of the steel girder 110 as shown in FIG. 4B, so that the center portion of the steel girder 110 may have a larger upwardly convex deflection displacement .

Here, the temporary concentrated load Fa can be performed, for example, by means of pulling down both ends of the steel girder 110 by installing a hydraulic jack (not shown).

Step 4 : As shown in FIG. 4C, a mold 130 for installing concrete is installed in a space in which the casing concrete 120 is to be synthesized. That is, the formwork 130 is installed so as to surround the upper flange 113 of the steel girder 110 and the upper end of the abdomen portion 112.

At this time, the formwork 130 may be installed to be supported on the ground on the ground, but the formwork 130 is installed on the steel girder 110. For example, the formwork 130 is mounted on the lower flange 111 of the steel girder 110 by means of a hatch 135. Since the formwork 130 is supported by the steel girder 110 so that the weight of the casing concrete 120 inserted into the formwork 130 is supported by the steel girder 110, It is possible to prevent it from acting on the concrete 120.

Step 5 : After step 4, the uncured concrete 120x is poured into the mold 130 from the pouring machine 60 to cure it as shown in Fig. 4D. At this time, the thickness of the concrete to be laid is determined such that a part of the front end coupling member 114 of the steel girder 110 is exposed to the outside of the surface of the casing concrete 120.

The amount of deflection of both end portions of the steel girder 110 of the min-like type is larger than that of the self-weight of the concrete due to the placement of the uncured concrete 120x, and the convex force displacement at the center portion becomes larger.

Step 6 : When the unhardened concrete 120x laid on the formwork 130 is sufficiently cured, the mold 130 is demolded as shown in FIG. 4E, and the damsels 135 supporting the molds 130 Remove. Thus, the casing concrete 120 is combined with the upwardly convexed steel girder 110.

Step 7 : Then, the temporary concentrated load Fa downward at both ends of the steel girder 110 is removed as shown in Fig. 4F, and the supporting point 55 is supported on the bridge (66 ') to both ends in the same manner as in the above-described conditions, thereby completing the fabrication of the steel composite girder (100).

The provisional concentrated load Fa introduced at both ends of the steel girder 110 is removed and the position of the support point 55 is moved to both ends 66 ' The tensile stress generated at the lower edge of the center portion of the girder is canceled by the compression prestress.

That is, the steel girder 110 is supported in a mining type, and the casing concrete 120 is synthesized on the neutral axis of the girder in a state in which the temporary concentrated load Fa is introduced, After the compression prestress is introduced into the lower edge of the center portion of the steel girder 110 by the weight of the mining portion and the weight of the casing concrete 120, the supporting point 55 of the girder is supported at both ends of the girder It is possible to offset the tensile stress generated at the lower edge of the center portion of the girder by the compressive prestress introduced into the lower edge of the middle portion of the steel composite girder due to the self weight of the steel girder and the weight of the casing concrete, By introducing tensile stress in advance to the girder upper part, the bottom plate concrete is synthesized on the upper part of the steel composite girder, Which can be obtained the advantage capable of offsetting compressive stress in advance.

On the other hand, according to another embodiment of the present invention, it is possible to exclude the configurations of Figs. 4B and 4F for applying and removing the temporary concentrated load Fa. Further, according to another embodiment of the present invention, steps 2, 3, and 7 may be omitted, in which the support point 55 is positioned in the form of a mining structure of the steel girder 110 and then the casing concrete is synthesized.

The end of the steel composite girder 100 according to the present invention is formed as an I-shaped cross-section in which the upper flange and the lower flange are coupled to the upper and lower ends of the abdomen, respectively, Shaped cross section so that it can effectively withstand the shear force acting largely at the end portion and by supporting the low cross sectional force at the center portion with a small amount of steel material, And a splitting crack 88 is generated in the casing concrete 120 which is synthesized at the neutral axis of the steel girder at the bridge portion (girder end) where the shear force is largely applied. It is possible to obtain an effect that can be solved.

6A to 6D, the casing concrete 120 is not synthesized at one or more ends of both ends of the girder length, but is formed in an empty area (for example, E may be provided. Such a configuration can be effectively used in the continuous bridge described later.

Hereinafter, a first embodiment of a method of constructing an upper structure of a bridge using the steel composite girder according to the present invention manufactured as described above will be described in detail with reference to FIG. 7A to FIG.

Step 1 : As shown in FIG. 7A, the casing composite 120 is not formed at one end, so that the steel composite girder 100 "provided with the hollow area E where the upper flange of the steel girder 110 is exposed, The empty area E of the girder 100 " is located above the bridge pier 52 forming the continuous fulcrum part, and the alternate (non-continuous) 51), the filled region of the girder 100 " (the area where the casing concrete is integrated to the end) is located.

Therefore, in the case of two consecutive spans, the empty area E is formed at only one end of the steel composite girder 100 ", but in the case of three consecutive spans or more, A formed girder (Fig. 6A) is used.

Step 2 : Then, as shown in Fig. 7B, the upper flange 113 of the hollow area E of the steel composite girder 100 "located on the upper side of the bridge pier 52 as the continuous point is connected to the connecting steel plate 190 At this time, the connecting steel plate 190 connects the upper flanges 113 adjacent to each other in the longitudinal direction by means of rivets, bolts, welding, or the like.

As a result, the connecting steel plate 190 can support the tensile stress acting on the neutral axis due to the completion of the bridge construction and the momentum acting on the continuous point portion.

Step 3 : Thereafter, a mold (not shown) for placing the bottom plate concrete 105 on the upper side of the steel composite girder 100 "and an upper flange 113 of the steel composite girder 100" (Not shown) for installing the composite concrete 106 filling the longitudinal side wall of the girder 100 " is provided together with the concrete. [0050] Next, concrete, which is not hardened, The bottom plate concrete 105 and the synthetic concrete 106 are synthesized at once on the steel composite girder 100 ". Next, the mold is demoulded and removed.

At this time, the front end connection member 114 fixed to the upper flange 113 of the steel composite girder 100 "assists the synthesis of the steel girder 110 and the casing concrete 120, but during the construction of the upper structure of the bridge, Thereby assisting the synthesis of the composite girder 100 "and the bottom plate concrete 105 so that the steel composite girder 100" and the bottom plate concrete 105 are firmly coupled to each other to perform integrated behavior.

In the method of constructing the bridge superstructure according to the embodiment of the present invention having the above-described structure, although the casing concrete 120 is synthesized on the upper part of the steel composite girder 100 ", the upper flange 113 is exposed As the space E is provided, the upper flange 113 of the steel composite girder 100 "exposed to the outside is connected to the connecting steel plate 190, so that the tensile stress due to the momentum It is possible to support the compressive stress of the neutral axis under the continuous point portion simultaneously with the placement of the bottom plate concrete and to be supported by the synthetic concrete integrally synthesized and to shorten the construction period It is possible to obtain advantageous effects.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

55: Support point 88: Split crack
100, 100 ': Steel composite girder 110: Steel girder
112: abdomen 113: upper flange
113a: groove 120: casing concrete
130: Form 105: Bottom plate concrete

Claims (8)

Shaped end section formed by an abdomen and a lower flange at a central portion and an I-shaped cross-section steel girder connecting an upper flange and the lower flange to the abdomen at an end portion thereof, Wherein the abdomen of the abdomen is provided with the abdomen which is higher than the abdomen at the end by a height of the upper flange, a groove for accommodating a part of the upper end of the abdomen is formed in the longitudinal direction, And the groove of the upper flange is welded to the groove of the upper flange to join the upper flange and weld the lower flange to form the steel girder , The length of the end portion of the I-shaped cross section of the steel girder is 0.05L to 0.33L of the girder length (L) A steel girder manufacturing step of manufacturing a washer;
A step of installing a front end connection member protruding upward on the upper flange;
A mold setting step of setting a mold in a form to surround the upper part of the abdomen of the steel girder and the upper flange;
A concrete synthesis step of synthesizing the casing concrete by placing the unhardened concrete in the mold to synthesize the casing concrete so that the upper end portion of the shear connection material is a height protruding from the upper surface of the casing concrete, Wow;
A die removing step of removing the die;
Wherein the steel composite girder is made of steel.
The method according to claim 1,
A steel girder supporting step for supporting the steel girder in simple numerical form so as to be supported at two points of support of L / 2 to L / 4 prior to the molding step;
A supporting point moving step of moving the supporting point so that the steel girder is supported at both ends after the die removing step;
The method of manufacturing a composite composite girder according to claim 1, further comprising:
The method according to claim 1,
Wherein the forming step is provided such that the formwork is supported by the steel girder.
3. The method of claim 2,
Introducing a temporary concentrated load downward at both ends of the steel girder after the step of supporting the steel girder;
After the concrete synthesis step, removing the temporary concentrated load;
Wherein the steel composite girder is made of steel.
5. The method according to any one of claims 1 to 4,
Wherein the mold composite is formed so as not to cover at least one of both ends of the steel girder, wherein the steel composite girder is formed with an end portion where the upper flange is exposed to the outside because the casing concrete is not synthesized, Characterized in that a continuous steel composite girder is provided.

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