KR101791062B1 - Method of manufacturing steel girder and steel girder manufactured using same - Google Patents

Abstract

The present invention relates to a method of manufacturing a prestressed steel girder, comprising the steps of: preparing a first girder formed of a steel material and including a "T" -shaped section of a first flange and a belly; A steel plate installing step of fixing the steel plate to the abdomen with the displacement displaced at the first position with respect to the abdomen of the first girder but with the rotational displacement allowed; A flexural load introducing step of introducing a flexural load in a direction in which a central portion of the first girder is convexed to the opposite side of the position of the first flange by a hydraulic jack via the steel plate; A second flange coupling step of coupling a second flange to the abdomen of the first girder in a state in which the first girder is bent and forming a steel girder having an I-shaped cross section; A bending load removing step of removing a bending load introduced by the hydraulic jack; A steel plate removing step of removing the steel plate from the abdomen; And the steel plate is hinged at two or more positions on the abdomen of the first girder and the flexural load is introduced into the hydraulic jack via the steel plate so that the reaction force necessary to introduce the flexural load into the first girder The present invention provides a prestressed steel girder and a bridge using the prestressed steel girder which are manufactured by introducing a precise compression prestress into a steel girder by supporting a steel plate and introducing a flexural load into the first girder stably.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a prestressed steel girder,

The present invention relates to a method of manufacturing a prestressed steel girder, and more particularly, to a prestressed steel girder which allows a pressurized prestress to be introduced into a lower flange of a steel girder so that a plate- will be.

In general, concrete has a high resistance to compressive stress and is inexpensive but has a disadvantage that it is vulnerable to tensile stress. Therefore, a bridge is constructed using a steel girder 10 having high resistance to tensile stress.

In order to shorten the curing time of the concrete in the process of manufacturing the girder supporting the load of the bridge deck, the plate-type bridge supporting the bridge deck 20 by only the I- This is simple and quick, so it is widely applied.

In other words, the plate-type bridge 9 carries the factory-made steel girder 10 to the construction site in advance, as shown in Figs. 1 and 2, and in most cases where the span length exceeds the conveyable length After the steel girder 10 is moved in the longitudinal direction, the steel girder 10 is placed on the lower structure 51 such as a pier or an alternate, and a mold is provided on the upper side of the mounted steel girder 10, And then installing the packing surface 30 and the railing 35 on the upper surface of the bottom plate concrete 20 after the steel plate is combined with the steel girder 10.

However, since the plate girder 9 has a relatively large amount of steel material used in the steel girder 20 for supporting the load acting on the bridge deck 20, there is a problem that the construction cost increases depending on the steel material consumption amount.

In order to overcome such a problem, a method of introducing compressive stress to the lower edge of the neutral axis of the steel girder 20 supporting the bridge deck 20 has been sought. However, introducing the compressive stress to the lower edge of the neutral axis of the steel girder 20 requires a very complicated and complicated process, and it is difficult to introduce a compressive stress of an accurate size, so that it can not be manufactured practically.

That is, according to Korean Patent Laid-Open Publication No. 10-2015-0075178, in a state in which the lower flange, the upper plate, and the upper flange are sequentially placed on the press apparatus, It is proposed to combine flanges to introduce compressive prestress into the lower flange using the force to restore the flexural deformation of the baffle plate.

However, since the cross section of the baffle plate is relatively small, there is a problem that the compression prestress is introduced into the lower flange by the bending deformation of the baffle plate, so that the efficiency is very low. Above all, it is very likely that buckling will occur in the process of generating bending deformation in the up and down direction of the biped plate. Therefore, there is a very strict limit to the process of installing the transverse bands on both sides of the biped plate in order to suppress lateral buckling. In addition, there is a problem in that it is difficult to introduce the force for bending the bend plate in the up and down direction even if the press apparatus is used, so that the compression prestress introduced into the lower flange is small.

As described above, a structure for introducing the compression prestress into the lower edge of the neutral axis of the steel girder has been suggested in the past, but the process of introducing the compression prestress into the lower flange of the steel girder is very complicated and requires complicated equipment. So that there is a risk of lateral buckling.

Thereby, there is a great need to simplify the process of introducing the compression prestress into the lower edge of the neutral axis of the steel girder and reliably suppress lateral buckling of the abdomen, and to securely manufacture the prestressed steel girder without complicated equipment .

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a steel girder having a high supporting ability by introducing a compressive prestress into a lower flange by a simple and quick process without any complicated equipment while reliably suppressing lateral buckling in the abdomen, And the like.

It is another object of the present invention to introduce a compressive prestress into a lower flange of an I-shaped cross-section of a steel girder in a simple and safe manner while introducing an accurate compression prestress.

It is another object of the present invention to reuse facilities used for introducing a compression prestress into a lower flange of a steel girder so that a prestressed steel girder can be manufactured in a batch without additional cost by using one facility.

It is another object of the present invention to construct a plate-like bridge having a high load-bearing capacity even with a smaller cross section by using the steel girder fabricated as described above.

According to the present invention, there is provided a method of manufacturing a steel girder, comprising the steps of: preparing a first girder formed of a steel material and including a T-shaped cross section of a first flange and a waist; A steel plate installing step of fixing the steel plate to the abdomen with the displacement displaced at the first position with respect to the abdomen of the first girder but with the rotational displacement allowed; A flexural load introducing step of introducing a flexural load in a direction in which a central portion of the first girder is convexed to the opposite side of the position of the first flange by a hydraulic jack via the steel plate; A second flange coupling step of coupling a second flange to the abdomen of the first girder in a state in which the first girder is bent and forming a steel girder having an I-shaped cross section; A bending load removing step of removing a bending load introduced by the hydraulic jack; A steel plate removing step of removing the steel plate from the abdomen; The present invention also provides a method of manufacturing a prestressed steel girder.

This is because the second flange is coupled to the abdomen of the first girder while the first flange is coupled to the abdomen of the abdomen in a state where the first girder is bent toward the first girder, The first flange and the abdomen coupled to each other are caused to act on the second flange coupled with the elastic restoring force to restore the original shape, To introduce a compression prestress into either the first flange or the second flange.

Here, since the first girder is formed such that the first girder section including the first flange and the abdomen except for the second flange of the steel girder has a high flexural rigidity, the magnitude of the flexural load introduced into the first girder is largely introduced It is possible to introduce a compressive prestress into the first flange and the second flange even more.

In particular, the present invention is characterized in that a steel plate is fixed to the abdomen of the first girder at a position where the displacement is restricted and the rotational displacement is allowed (i.e., the hinge is engaged) at two or more positions, Since the steel plate supports the reaction force necessary for introducing the flexural load into the first girder so that the process of introducing the flexural load into the first girder can be performed stably through the steel plate Can be obtained.

In addition, since the steel plate is hinged to the first girder, the first girder is in a state in which the displacement in the up-and-down and left-right directions is restricted with respect to the steel plate and the rotational displacement is allowed. In the process of introducing the load, the advantage that the bending load introduced by the hydraulic jack acts as a load that causes the bending deformation of the first girder all without loss, has an advantage that the introduction efficiency of the bending load is improved.

In addition, since the steel plate is coupled to the abdomen of the first girder, there is a risk that lateral buckling occurs in the abdomen where compressive stress acts in the process of introducing a flexural load into the first girder, So that it is possible to obtain an advantageous effect that a safe flexural load can be introduced even without a facility for suppressing lateral displacement of the abdomen of the first girder.

That is, according to the present invention, a flexural load is applied to the first girder by a hydraulic jack via a steel plate in a state where the steel plate is hingedly connected at two or more places of the abdomen of the first girder, Since all of the girders are used to induce the flexural deformation of the first girder, the load transfer efficiency is improved, and the flexural deformation of the first girder is generated, while the abdomen section is reinforced by the steel plate, It is possible to obtain an advantageous effect of accurately introducing the introduced compression prestress more accurately because the safety is ensured even when there is no installation inconvenience and the accurate load is introduced into the first girder and the compression prestress is introduced into the first flange and the second flange.

Meanwhile, according to a preferred embodiment of the present invention, the first flange is a lower flange, and the second flange is formed as an upper flange. That is, when the first flange is formed as a lower flange, a high compressive stress is introduced into the first flange by the flexural load introduced into the first girder by using the hydraulic jack, and in this state, As the flange is coupled to the upper flange, the bending deformation introduced into the first girder by the upper flange can not be completely restored to the original shape, but only partially. Therefore, the first flange (lower flange) A compression prestress is introduced into the lower abdomen of the girder.

As a result, the prestressed steel girder which has been manufactured is introduced not only with the lower flange but also with the compressive prestress in the lower part of the neutral axis, thereby maximizing the size of the compression prestress introduced into the steel girder. A height advantageous effect can be obtained.

At this time, the second flange is formed in a larger cross-section than the first flange, thereby reducing the extent to which the first girder returns to its original shape, thereby reducing the compression of the compression flanges of the compressive prestress introduced into the lower flange of the steel girder, The size can be further increased.

Here, the bending load introducing step is performed by the first girder being performed in a posture of a "ㅗ" -shaped section, and the first girder introducing a convex bending deformation toward the upward direction.

The method according to claim 1, further comprising: a girder supporting step of supporting, at a position spaced apart from both ends of the first girder, By doing so, it is possible to obtain an advantage that the manufacturing is facilitated and the safety is ensured without hanging the first girder or installing a complicated press facility.

In this case, it is preferable that a position for supporting the first girder in the mining form is defined as two positions where the steel plate is hinged to the abdomen of the first girder. As a result, when a force is applied to the first girder with respect to the steel plate by the hydraulic jack, when the first girder is flexurally deformed, flexural deformation is generated around the two support points to induce smooth flexural deformation.

It is preferable that at least one of the supporting points for supporting the first girder is provided so as to be movable in the longitudinal direction of the first girder. Thus, the first girder can be stably mounted even if the first girder is deformed in the horizontal direction to change the horizontal distance between the two hinges connected to the steel plate.

According to another embodiment of the present invention, the first flange is an upper flange, and the second flange is a lower flange. That is, when the first flange is formed as the upper flange, tensile stress is introduced into the lower edge of the abdomen in a state in which the first jacket is bent by the hydraulic jack. In this state, The first girder combined with the upper flange and the abdomen can introduce the compressive prestress into the lower flange (second flange) by the elastic restoring force to restore the original shape.

When a steel girder is manufactured as described above, a tensile prestress is introduced to the lower side of the neutral axis of the abdomen. However, since the steel has a high resistance against the tensile force, the girder does not exceed the degree of breakage caused by the bottom plate or live load, The tensile stress acting on the lower edge can be canceled by the compression prestress introduced into the lower flange as described above.

In the flexural load introduction step, the first girder is performed in a posture having a tapered shape, and the first girder can be introduced with a convex bending deformation toward the downward direction.

To this end, the apparatus may further include a girder suspending step for suspending the first girder in the air prior to the flexural load introduction step, and the second flange joining step may be performed while the first girder is suspended in the air.

Accordingly, by introducing a flexural load into the first girder by the hydraulic jack, it is possible to smoothly perform the bending deformation in the direction in which the central portion of the first girder is convex downward without interference with the ground. At the same time, The process of joining the flange to the abdomen of the first girder can be performed smoothly, so that the manufacturing process of the prestressed steel girder becomes much easier and the introduction of the precastress can be guaranteed.

On the other hand, the second flange forming the lower flange is formed to have a larger cross-section than the first flange, so that the resistance capability at a position where a high tensile stress acts on the bridge can be improved, It is possible to accommodate the lower flange of the large cross section in the compressive prestress, thereby increasing the resistance capability.

In addition, the abdomen of the first girder is formed in a convex arch shape upward in a state in which no flexural deformation is generated, so that the abdomen of the final fabricated girder is also held upward in a slightly convex arch shape. As a result, a downward load is applied by the load of the bottom plate concrete synthesized on the upper surface of the steel girder, resulting in a straight line shape close to the horizontal line.

On the other hand, the first position may be defined as two or more positions spaced from both ends of the first girder. Thereby, while exerting a force to push the first girder to the hydraulic jack via the steel plate, the flexural load can be introduced into the first girder while the steel plate maintains its position with respect to the first girder.

The first position may be defined as a distance L / 5 to 3L / 5 of the length L of the first girder from both ends of the first girder. This is because, when a flexural load is introduced into the first girder and a bending deformation occurs, an upward displacement and a downward displacement are generated based on a position spaced by L / 4 from both ends, This is because it is possible to maximize the deflection displacement due to the small flexural load. However, the present invention is not limited to the positions separated by L / 4 from both ends, and a similar effect can be obtained at positions separated by approximately L / 4. Here, approximately L / 4 may be a position spaced apart by L / 5 to 3L / 5, which is located with a deviation of approximately 1/20 to 3/20 of the girder length L. [

Thus, as the steel plate is constrained to the abutment of the first girder at a distance of approximately L / 4 from both ends and the rotational displacement is combined in an allowable hinge configuration, the magnitude of the force introduced by the hydraulic jack is made possible It is possible to introduce a high compressive prestress by an elastic restoring force that restrains the flexure deformation of the first girder on the second flange coupled to the abdomen of the first girder.

The steel plate is formed to have a larger flexural rigidity than the first girder so that when a flexural load is applied to push the first girder through the steel plate by the hydraulic jack, 1, and most of the flexural load introduced by the hydraulic jack acts as a flexural deformation of the first girder, so that the amount of flexural deformation can be maximized. Further, it is possible to stably push the first girder as the steel plate keeps the original shape almost by the reaction force of the flexural load pushing the first girder.

Here, the steel plate may be installed only on one side of the abdomen, but according to a preferred embodiment of the present invention, the steel plate may be installed on both sides of the abdomen. Thus, since the steel plate is provided on both side surfaces of the abdomen, the lateral buckling caused by the compressive stress acting on the abdomen can be completely suppressed by the steel plate having high lateral stiffness, and safety can be ensured. In some cases, as the force for pushing the first girder by the hydraulic jack is introduced from both sides of the abdomen, a flexural load is introduced symmetrically on both sides of the abdomen, so that the girder can be prevented from turning in the lateral direction.

For example, in the bending load introducing step, the hydraulic jack is installed on either the steel plate or the first flange at the positions of the both ends of the first girder, and the hydraulic jack causes the first flange To the upper side. By arranging the hydraulic jacks at both ends of the first girder in this way, the amount of bending deformation of the first girder can be maximized by the force introduced by the hydraulic jack, and by pushing the first flange protruding laterally with respect to the abdomen, 1 It is possible to smoothly introduce the vertical bending load into the girder.

On the other hand, in another embodiment of the present invention, the hydraulic jack is installed to be coupled to both the first flange and the steel plate at the center portion of the girder, and the same action can be realized by pulling the first flange.

In the meantime, the present invention provides a steel girder which is manufactured as described above and in which a compression prestress is introduced into the lower flange.

According to another aspect of the present invention, there is provided a bridge structure comprising: a bridge girder including the steel girder and resting on the bridge foundation; A bottom plate concrete synthesized on the upper side of the steel girder; To provide the bridge constructed.

Here, the bridge girder is constituted by connecting a plurality of segment girders in the longitudinal direction, and the steel girder may be disposed only in a central portion of a section where the moment of the bridge of the bridge girder acts. As described above, the prestressed steel girder in which the compressive prestress is introduced into the lower flange is disposed only in the section where the moment is exerted. In the section where the moment hardly acts, the prestressed steel girder is disposed as a steel girder It can also reduce the cost of doing so.

The bottom plate concrete is formed on the upper side of the upper flange of the bridge girder so that the neutral axis of the composite section of the bridge girder and the bottom plate concrete is located on the upper side of the prestressed steel girder The upper flange or the vicinity thereof), tensile stress acting on the bridge acts on only the steel girder, thereby enhancing the efficiency of supporting the tensile stress in the bridge.

The steel composite girder according to the present invention can be widely applied to civil engineering structures other than bridges.

 As described above, according to the present invention, a second flange is engaged in a state in which a flexure load is introduced into a first girder previously formed including a first flange and a belly portion, and a flexure load An advantageous effect of safely and efficiently manufacturing the prestressed steel girder by introducing the compression prestress into the first flange and the second flange can be obtained.

Particularly, in the present invention, when the first flange is formed as a lower flange and the second flange is formed as an upper flange, not only a compression prestress can be introduced into the lower flange of the steel girder but also, A compressive prestress is introduced into the prestressed steel girder having a higher load carrying capacity.

At the same time, according to the present invention, when the first flange is formed as a lower flange and the second flange is formed as an upper flange, the first flange and the abdomen are joined together to form a prestressed steel girder Can be obtained.

In addition, in the present invention, even if the first flange is formed as the upper flange and the second flange is formed as the lower flange, the first flange and the abdomen are combined to form the lower flange using the elastic restoring force of the first girder. 2 Since the compression prestress is introduced into the flange, a prestressed steel girder with improved load carrying capability can be manufactured.

In the present invention, the steel plate is hinged at two or more positions on the abdomen of the first girder and the flexural load is introduced into the hydraulic jack via the steel plate, so that it is necessary to introduce a flexural load into the first girder It is possible to stably perform the process of introducing the flexural load into the first girder by supporting the reaction force on the steel plate.

In the present invention, since the steel plate is hinged to the first girder, the first girder is in a state in which the displacement in the up-and-down and left-right directions is restrained with respect to the steel plate and the rotational displacement is allowed. In the process of introducing the bending load into the first girder, the advantage that the bending load introduced by the hydraulic jack acts as a load causing all the bending deformation of the first girder without loss is obtained, and the introduction efficiency of the bending load is also improved.

First of all, according to the present invention, since the steel plate having a relatively large cross section is hinged to the abdomen of the first girder, the lateral buckling which can be generated while compressive stress acts on the abdomen in the process of introducing the flexural load into the first girder The steel plate is naturally relieved while reinforcing the end face of the abdomen of the first girder so that it is possible to obtain a favorable effect of enabling the safe introduction of the flexural load even without equipments for restraining the lateral displacement of the abdomen of the first girder .

Further, according to the present invention, since the thickness of the steel plate is made larger than that of the abdomen, the flexural load introduced into the first girder is more reliably supported by the steel plate, so that the magnitude of the flexural load introduced into the first girder It is possible to introduce a larger compression prestress into the lower flange coupled to the abdomen, and since the flexural load introduced by the hydraulic jack is accurately transmitted to the first girder, the advantage of being able to accurately control the size of the compression prestress to be introduced Can be obtained.

1 is a front view showing a configuration of a general plate-type bridge,
2 is a cross-sectional view taken along line II-II in Fig. 1,
3 to 8E relate to a method of manufacturing a prestressed steel girder according to a first embodiment of the present invention,
3 is a perspective view showing a first girder manufactured in advance to manufacture a prestressed steel girder according to an embodiment of the present invention,
Fig. 4A is an exploded perspective view showing a structure for coupling a steel plate to a first girder, Fig.
4B is an exploded perspective view showing a structure according to another embodiment of the present invention for joining a steel plate to a first girder,
5 is a front view showing a configuration in which a hydraulic jack for introducing a flexural load is installed in the first girder,
FIG. 6 is an enlarged view of a portion 'A' in FIG. 5,
7 is a cross-sectional view taken along the section line VII-VII in FIG. 6,
FIGS. 8A to 8E sequentially illustrate the construction of a prestressed steel girder by installing a hydraulic jack on the first girder of FIG. 5, introducing a flexural load,
9A to 12 relate to a method of manufacturing a prestressed steel girder according to a second embodiment of the present invention,
9A and 9B are perspective views showing a first girder manufactured in advance to fabricate a prestressed steel girder according to a second embodiment of the present invention,
Fig. 10A is a front view showing a configuration in which a hydraulic jack for introducing a flexural load is installed in the first girder; Fig.
Fig. 10B is a front view showing a configuration in which a hydraulic jack for introducing a flexural load is installed in a first girder in which a camber is formed; Fig.
Figs. 11A to 11E sequentially illustrate the construction of a prestressed steel girder by introducing a flexural load into the first girder of Fig. 10A and coupling the lower flanges,
FIG. 12 is a view showing a prestressed steel girder manufactured by introducing a flexural load into the first girder of FIG. 10B in which a camber is formed and coupling a lower flange;
FIG. 13A is a front view showing a girder for a bridge manufactured by connecting the prestressed steel girder of FIG. 12;
Fig. 13B is a view showing a structure for mounting the manufactured bridge girder on a lower structure, Fig.
13C is a view showing a state in which a bottom plate concrete is synthesized on the upper side of a bridge girder,
Fig. 13D is a cross-sectional view taken along line XX in Fig. 13C.

Hereinafter, 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.

8E, the prestressed steel girder 100 according to the first embodiment of the present invention includes a first flange 111 forming a lower flange, a second flange 140 forming an upper flange, A first flange 140 formed of a steel material having an I-shaped cross section and composed of an abutment portion 112 connecting the first flange 140 and the second flange 140 to cancel the tensile stress acting on the steel girder 100, A compressive prestress is introduced into the lower abdomen 112 of the neutral axis.

The prestressed steel girder 100 may have a larger cross section of the second flange 140 than the first flange 111 so that the amount of bending deformation introduced into the first girder 110 is restored It is possible to introduce a higher compression prestress into the lower flange 111. [

5, the abdomen 112 may be formed as a straight line in a state in which a compressed prestress is not introduced into the lower flange. In another embodiment of the present invention, It may be formed in an upward convex arch shape. Thus, the amount of the camber that rises above the final fabricated girder is adjusted so that the bottom plate concrete 20 is deflected downward by the weight of the bottom plate concrete 20 in a state where the bottom plate concrete 20 is synthesized on the upper side of the steel girder And may be configured to be straight in a horizontal direction.

Hereinafter, a method of manufacturing the prestressed steel girder 100 in which the compression prestress is introduced into the belly portion 112 and the second flange 140 below the neutral axis will be described in detail.

Step 1 : First, as shown in FIG. 3, the first flange 111 and the abdomen 112 are combined to produce a first girder 110 having a "T" (or "ㅗ" do. As shown in the drawing, the first girder 110 is formed in a 'T' shape in its entire cross section. If necessary, the first girder 110 may include a first flange 111 in a part of a region excluding a portion pressurized by the hydraulic jack 130, Or may be formed as a cross-section.

A through hole 112a is formed in the abdomen portion 112 at a first position spaced apart by approximately L / 4 of the length L of the first girder 110 from both ends of the first girder 110. Here, the position of the through hole 112a is most preferably spaced by L / 4 from both ends, but it may be in the range of about L / 5 to 2L / 5. It is preferable that the height H of the through hole 112a is located on the neutral axis of the first girder 110. [

Step 2 : Then, as shown in Fig. 4A, the steel plate 120 is fixed at two first positions on the abdomen 112 of the first girder 110. Fig. The through hole 112a of the abdomen portion 112 and the through hole 120a of the steel plate 120 are passed through the hinge bolt 88 and the end of the hinge bolt 88 is fastened by the nut 89 .

The steel plate 120 and the abdomen portion 112 are connected to each other via the hinge bolt 88 passing through the aligned through holes 112a and 120a so that the steel plate 120 is moved up and down And the hinge joint permitting rotational displacement with respect to the abdomen portion 112 is performed in two places.

It is preferable that the steel plate 120 has a larger cross section than the section modulus of the first girder 110. For example, the thickness t2 of the steel plate 120 may be formed to be greater than the abdomen thickness t1 of the first girder 110, and as shown in Fig. 4A, 120 may be coupled to both sides of the abdomen 112 of the first girder 110 so as to have greater flexural rigidity than the first girder 110.

When the flexure load P is applied to push the first girder 110 into the hydraulic jack 130 via the steel plate 120, the first girder 110 The stroke of the hydraulic jack necessary to induce the predetermined bending deformation of the first girder 110 is not increased so that the capacity of the hydraulic jack is kept small while the bending load of the hydraulic jack 130 It is possible to minimize the occurrence of instability due to a longer stroke and to stably induce the flexure deformation of the first girder 110.

As shown in the figure, it is most preferable that the first position where the steel plate 120 and the abdomen portion 112 are fixed by the hinge bolt 88 is determined to be two, but the position instability due to mutual deformation But it may be installed at one or more than three, as needed. However, as will be described later, the number of the steel plates 120 is determined within a range in which the first girder 110 is allowed to be deformed flexibly.

4A, when the steel plate 120 is fixed to the both side surfaces of the abdomen portion 112, the bending load P is introduced into the first girder 110 and the bending deformation of the first girder 110 The lateral buckling of the abdomen portion 112 is restrained on both sides by the compressive stress acting on the abdomen portion 112 of the first girder 110 so that the lateral buckling of the first girder 110 is completely suppressed It is possible to obtain an advantageous effect.

Meanwhile, as shown in FIG. 4B, the steel plate 120 may be fixed to only one side of the abdomen 112. Even in this case as well, since the stiffness of the abdomen 112 is reinforced by the steel plate 120 having a thick cross section, when the bending load P is introduced into the first girder 110, The occurrence of lateral buckling can be almost completely suppressed.

According to another embodiment of the present invention, the flexural rigidity of the steel plate 120 may be equal to or smaller than the flexural rigidity of the first girder 110. In this case, The stroke of the hydraulic jack 130 necessary for introducing the bending load P into the girder 110 is selected to be larger and the bending deformation amount of the first girder 110 is larger than the displacement that pushes the hydraulic jack 130 to the hydraulic jack 130 It can be done in the form of taking a small sum.

The length of the steel plate 120 may be longer than the length L of the first girder 110. Although not shown in the drawings, the steel plate 120 may further include a restraining member (not shown) for restraining both ends of the steel plate 120 against the ground. Thus, the entire stroke of the hydraulic jack 130 induces the bending deformation of the first girder 110, and the bending deformation of the first girder 110 is stably performed, thereby minimizing the stroke of the hydraulic jack 130. [

Here, the first girder 110 forms a lower flange, so that the first girder 110 can be supported on the ground by two or more supporting points as shown in FIG. Preferably, the first girder 110 is supported in an underside form by disposing support points below the first position where the steel plate 120 is hinged by the hinge bolts 88. Here, the support point can be defined within a deviation range of L / 10 from the lower side of the first position. This makes it possible to stably support the supporting point at a position where the vertical variation of the first girder 110 is the smallest even when the first girder 110 is bent upwardly convexly with respect to the steel plate 120 And it is also possible to avoid the interference between the supporting point and the displacement of pushing the first flange 111 of the first girder 110 by the hydraulic jack 130.

Step 3 : When the steel plate 120 is fixed to the abdomen of the first girder 110 in step 2, a hydraulic jack 130 for introducing a flexural load P to the first girder 110 is installed. The hydraulic jack 130 may be supported by the first girder 110 or may be supported by the steel plate 120.

6 and 7, in order to introduce a flexural load P into the first girder 110 when the hydraulic jack 130 is installed on the steel plate 120, The steel plate 120 can be coupled to the first girder 110 in a state in which the steel plate 120 is integrally formed with the steel plate 120. Accordingly, can do.

The hydraulic jack 130 includes a cylinder 131 in which a hydraulic chamber is formed and a plunger 132 which is drawn out from the cylinder 131 by a force acting as a flexural load P in accordance with the pressure of the hydraulic chamber. A support plate 112x is coupled to the steel plate 120 to bring the bottom surface of the hydraulic jack 130 into close contact with the hydraulic jack 130 so as to introduce a flexural load P to the first girder 110 by the hydraulic jack 130, So that the reaction force of the flexural load P pushing the first girder 110 downward is supported by the steel plate 120. Accordingly, it is possible to stably apply the flexural load P to the first girder 110 by the hydraulic jack 130 via the steel plate 120.

The fixing bracket 138 for fixing the outer circumferential surface of the hydraulic jack 130 is fixed to the steel plate 120 by the fixing bolt 138a so that the hydraulic jack 130 can be rotated while the steel plate 120 is applying the flexural load P. [ Thereby stably fixing the posture of the user.

A support member 135 capable of resilient deformation is interposed between the first flange 111 and the hydraulic jack 130 so that a flexural load P is transmitted from the hydraulic jack 130 to the first flange 111 The flexure load P from the hydraulic jack 130 is transmitted to the first flange 111 in a direction perpendicular to the first flange 111 due to the elastic deformation of the support member 135, .

The hydraulic jack 130 is fixed to the steel plate 12 at both ends of the first girder 110 and pushes the first flange 111 downward. However, when the hydraulic jack 130 is mounted on the first girder The hydraulic jack 130 may be configured to press the steel plate 120 at the center of the first girder 110 and the steel plate 120 at the central portion of the first girder 110. The hydraulic jack 130 may be fixed to the first flange 111 at both ends of the first girder 110, The cylinder 131 and the plunger 132 may be fixed to the flange 111 so that the hydraulic jack 130 may be pulled out.

8A, a flexural load P is applied from the hydraulic jack 130 installed at both ends of the first girder 110 toward the first flange 111 of the first girder 110. As shown in Fig. At this time, since the steel plate 120 is fixed to the first girder 110 in a state where the first displacement of the steel plate 120 can be rotationally displaced to the first position of the first girder 110, 1 both ends of the girder 110 are pushed downward and a flexural load P acts on the first girder 110 in a direction in which the central portion thereof is upwardly convexed and the first girder 110 ), A convex deflection displacement occurs in the central portion upward.

Accordingly, the first girder 110 is in a state in which compressive stress acts on the lower side of the abdomen portion 112 and the first flange 111 with respect to the neutral axis. In particular, since the first girder 110 is flexibly deformed while being coupled with the first flange 111, a large flexural load P can be introduced by the hydraulic jack 130 to increase the amount of flexural deformation, A high compressive stress can be introduced to the first flange 111 of the first girder 110 and the neutral axis.

8A to 8E, in order to facilitate understanding, a flexural load P is introduced into the first girder 110 formed as a horizontal straight-line abdomen shown in FIG. 5, so that the center portion of the girder is convex upward Is shown in a state where a displacement is generated.

Step 4 : Then, as shown in FIG. 8A, when the flexure load P is introduced into the first girder 110 by the hydraulic jack 130, and the first girder 110 is warped at a predetermined curvature , The second flange 140 preliminarily formed at a predetermined curvature as shown in Fig. 8B is coupled to the upper end of the abdomen of the first girder 110. [ That is, the second flange 140 forms the upper flange of the prestressed steel girder.

The curvature of the second flange 140 coincides with the curvature of the upper end of the abdomen 112 of the first girder 110. The curvature of the second flange 140 coincides with the curvature of the upper end of the abdomen 112 of the first girder 110, . When the second flange 140 is coupled with the upper end of the abdomen of the first girder 110 in a convexly bent state, the first girder 110 is elastically deformed in its original form by the second flange 140 It is possible to increase the size of the first flange 111, which is the lower flange of the finally manufactured steel girder 100, and the compression prestress, which is introduced into the abdomen below the neutral axis.

In addition, since the cross section of the second flange 140 is formed larger than the first flange 111, the amount by which the amount of flexural deformation of the first girder 110 is restored in Step 5 can be reduced, The compressive prestress introduced into the first flange 111 of the flange 110 can be increased.

Since the upper portion of the abdomen portion 112 of the first girder 110 is an empty space because the first girder 110 is stationary on the ground due to the supporting point, This is naturally arranged.

The process of joining the second flange 140 with the first girder 110 may be performed by bolt fastening using a bracket, but it is most effective to be performed by welding. To this end, after the second flange 140 is subjected to the primary bonding by spot welding at a plurality of positions of the contact portions of the first and second girders 110 and 112 in contact with each other, The flange 140 and the abdomen portion 112 of the first girder 110 are first bonded to each other so that the welding rod of the welding apparatus moves along these portions 112 and 140 while firmly securing the secondary . 11C, the second flange 140 is coupled to the first girder 110 as an upper flange to become an I-shaped section steel girder.

According to another embodiment of the present invention, the joining of the second flange 140 to the first girder 110 may be performed by the fillet welding or the like immediately at the contact portion between the abdomen portion 112 and the second flange 140 have.

The state in which the flexure load P is applied from the hydraulic jack 130 is maintained while the second flange 140 is engaged with the first girder 110. [

Step 5 : Thereafter, as shown in Fig. 8D, the bending load P applied by the hydraulic jack 130 is no longer applied, and the bending load P applied to the first girder 110 is increased, Is removed.

The first girder 110 including the first flange 111 and the abdomen portion 112 is elastically restored in a direction 110r in which the center portion thereof is downwardly convexed and the elastic restoring force acts on the upper portion of the abdomen portion of the first girder 110 The elastic restoration amount of the first girder 110 by the combined second flange 140 is limited to a part. A portion of the compressive stress introduced under the first flange 111 and the belly portion 112 is removed while the flexure load P is applied to the first girder 110 in Step 3, The compression prestress is introduced to the lower side of the first flange 111 and the abdomen portion 112 by the amount of the bending deformation which is not restored by the interference of the first flange 111 and the abdomen portion 112. [

8E, the steel plate 120 hinged to the abdomen portion 112 of the first girder 110 and the hydraulic jack 130 are removed so that the first flange 111 and the second flange 111 The fabrication of the prestressed steel girder 100 formed by the flange 140 and the abdomen portion 112 connecting these flanges 140 and 140 is completed. The steel plate 120 and the hydraulic jack 130 used for manufacturing the steel girder 100 are reused to fabricate another prestressed steel girder 100. [

As described above, the steel girder 100 manufactured by the method according to the first embodiment of the present invention is constructed such that the steel plate 120 is hinged to the abdomen portion 112 of the first girder 110 at two first positions, Since the reaction force required to introduce the flexural load P to the first girder 110 is supported by the steel plate 120 because the flexural load is introduced into the hydraulic jack through the steel plate 120, It is possible to introduce the process of introducing the flexural load P into the girder 110 in a stable and precise size.

The first flange 111 of the first girder 110 is formed as a lower flange and the second flange 112 is formed as an upper flange so that the prestressed steel girder can be easily Not only the first flange 111 which is the lower flange but also the compression prestress is introduced to the lower side of the abdomen 112, so that an advantageous effect of realizing a higher load carrying capacity can be obtained.

The steel plate 120 is moved in two first positions to minimize the influence of the flexure deformation of the first girder 110 while the first girder 110 is accurately introduced with the flexural load P, The bending stiffness of the steel plate 120 is greater than the bending stiffness of the first girder 110 or the both ends of the steel plate 120 are constrained The amount of flexure of the first girder 110 can be maximized by the flexural load P applied to the hydraulic jack 130 so that the flexural load applied to the first girder 110 P and the amount of flexural deformation can be accurately controlled, and a predetermined compression prestress can be accurately introduced.

In addition, the present invention is characterized in that a compressive force resulting from the flexural deformation of the first girder 110 is transmitted to the abdomen portion (not shown) by the steel plate 120 installed to accurately apply the flexural load P to the first girder 110 112 are fundamentally restrained by lateral buckling which may be caused by the action of the prestressed steel girder 112, thereby obtaining a prestressed steel girder safely.

Hereinafter, a second embodiment of the present invention will be described in detail with reference to Figs. 9A to 12. However, in describing the second embodiment of the present invention, the detailed description of the functions or configurations described in the first embodiment will be omitted for the sake of clarity of the second embodiment.

11E and 12, a prestressed steel girder 200 according to a second embodiment of the present invention includes a first flange 211 forming an upper flange, a second flange 211 forming a lower flange, And a second flange 240 which is formed of a steel material having an I-shaped cross section and which has an abdominal portion 212 connecting the first and second flanges 240 and 240 to cancel the tensile stress acting on the steel girder 200, Lt; RTI ID = 0.0 > prestress < / RTI >

The prestressed steel girder 200 may have a larger cross section of the second flange 240 than the first flange 211 so that the lower flange is formed at the amount of flexure introduced into the first girder 210 It is possible to introduce a higher compression prestress into the second flange 240.

10A, the abdomen 212 may be formed as a straight line in a state in which the compression prestress is not introduced into the second flange 240. However, as shown in Fig. 10B, And the steel girder 210 'of FIG. 12, which is finally manufactured, can be manufactured so that a camber protruding upward is formed. In this state, the bottom plate concrete 20 is synthesized on the upper side of the steel girder 210 ', and it can be formed in a straight horizontal shape in a state where the bottom plate concrete 20 is deflected downward by its own weight have.

Hereinafter, a method of manufacturing the prestressed steel girders 200, 200 'in which the compression prestress is introduced into the second flange 240 will be described in detail.

Step 1 : First, the upper flange 211 and the abdomen 212 are joined to fabricate a first girder 210 having a T-shaped cross section. The first girder 210 may be formed in the shape of a 'T' in its entire cross section. However, in some of the regions other than the portion pressed by the hydraulic jack 130, the upper flange 211 may not be formed, .

The through hole 212a is formed in the abdomen 212 at the first position, which is a distance L1, L2 spaced apart by approximately L / 4 of the length L of the first girder 210 from both ends of the first girder 210. [ . As in the first embodiment, the position of the through hole 212a is most preferably spaced by L / 4 from both ends, but it may be in the range of about L / 5 to 2L / 5. The height H of the through hole 212a is preferably located on the neutral axis of the first girder 210. [

Step 2 : Then, as shown in FIG. 9A, the steel plate 120 is fixed to the abdomen portion 212 of the first girder 210 at two first positions. The through hole 212a of the abdomen 212 and the through hole 120a of the steel plate 120 are passed through the hinge bolt 88 and the end of the hinge bolt 88 is fastened by the nut 89 .

The steel plate 120 and the abdomen 212 are connected via the hinge bolts 88 passing through the aligned through holes 212a and 120a so that the steel plate 120 is moved up and down And the hinge joint permitting rotational displacement with respect to the abdomen 212 are performed in two places. Here, it is preferable that the steel plate 120 has a larger cross section than the section modulus of the first girder 210. .

9A, when the steel plate 120 is fixed to both side surfaces of the abdomen portion 212, the bending load P is introduced into the first girder 210, and the bending strain of the first girder 210 The transverse buckling of the abdomen portion 212 is restrained on both sides by the compressive stress acting on the abdomen portion 212 of the first girder 210 so that the lateral buckling of the first girder 210 is completely suppressed It is possible to obtain an advantageous effect.

Meanwhile, as shown in FIG. 9B, the steel plate 120 may be fixed to only one side of the abdomen 212. Even in this case, the stiffness of the abdomen 212 is reinforced by the steel plate 120 having a thick cross section. Therefore, when the bending load P is introduced into the first girder 210, The occurrence of lateral buckling can be reduced.

Here, the length of the steel plate 120 may be longer than the length L of the first girder 210. Although not shown in the drawings, the steel plate 120 may further include a restraining member (not shown) for restraining both ends of the steel plate 120 against the ground. Thus, the entire stroke of the hydraulic jack 130 induces the bending deformation of the first girder 210, and the bending deformation of the first girder 210 is stably performed, thereby minimizing the stroke of the hydraulic jack 130. [

Here, since the first girder 210 has a T-shaped cross section, the first girder 210 is suspended with the wire 90 so that the first girder 210 is at a predetermined position.

Step 3 : When the steel plate 120 is fixed to the abdomen of the first girder 210 in step 2, then the hydraulic jack 130 for introducing the flexural load P to the first girder 210 is shown in Figs. It is installed in the form illustrated in FIG. The hydraulic jack 130 may be supported by the first girder 210 or may be supported by the steel plate 120.

11A, a flexural load P is applied from the hydraulic jack 130 provided at both ends of the first girder 210 toward the first flange 211 of the first girder 210. As shown in Fig. At this time, since the steel plate 120 is fixed to the first girder 210 in a state where the first displacement of the first girder 210 can be rotationally displaced while the displacement thereof is restricted, 1 both ends of the girder 210 are lifted upward so that a flexural load P acts on the first girder 210 in a direction in which the central portion is convex downward and the first girder 210 ), A convex deflection displacement occurs downward.

11A to 11D, for the sake of understanding, a flexural load P is introduced to the first girder 210 formed as a horizontal straight-line-shaped abdomen shown in FIG. 9A so that the center portion of the girder is convex downward Is shown in a state where a displacement is generated. 9B, the bending load P can be introduced in a downward convex direction. In this case, even if the bending deformation does not reach a downward convexity, the center portion of the girder is moved downward And a state in which the flexural load P acts in the direction of being convex.

Step 4 : Then, as shown in FIG. 11A, when the flexure load P is introduced into the first girder 210 by the hydraulic jack 130, and the first girder 210 is bent at a predetermined curvature , The second flange 240 preliminarily manufactured with a predetermined curvature as shown in FIG. 11B is coupled to the lower end of the abdomen of the first girder 210.

The work space necessary for coupling the second flange 240 to the abdomen portion 212 of the first girder 210 is formed by the wire 90 1 < / RTI > Although the process of joining the second flange 240 with the first girder 210 may be performed by bolting using a bracket, it is effective to be performed by welding. 11C, the second flange 240 is coupled to the first girder 210 to form an I-shaped section steel girder.

The state in which the flexure load P is applied from the hydraulic jack 130 is maintained even while the second flange 240 is engaged with the first girder 210. [

Step 5 : Then, as shown in FIG. 11D, the wire 90 pulling up the first girder 210 is moved downward (90d ') and placed on the cradle, and the flexural load (P) is no longer applied, and the flexural load (P) applied to the first girder (210) is removed.

The first flange 210 and the second flange 210 are connected to the second flange 240 coupled to the abdomen 212 by an elastic restoring force in a direction in which the central portion of the first flange 211 and the abdomen portion 212 are convex upward Compressed prestressing is introduced.

The steel plate 120 and the hydraulic jack 130 hinged to the abdomen portion 212 of the first girder 210 are then removed and the first flange 211 and the second flange 240 and the second flange 240 And 240 are connected to each other, the fabrication of the prestressed steel girder 200 is completed.

On the other hand, when the prestressed steel girder 200 'is manufactured using the first girder 210' of the arcuate abdomen 212 shown in FIG. 5B, as shown in FIG. 12, The manufacture of the steel girder 200 'is completed with the raised camber being formed.

The prestressed steel girders 100, 200, 200 'according to the present invention manufactured as described above can be manufactured in factories and transported to construction sites of various civil structures, and can be applied to construction, and particularly, can be used for construction of plate type bridge.

That is, the prestressed steel girders 100, 200, 200 'conveyed to the construction site are connected to each other in the longitudinal direction and connected to each other by a bridge girder 100x having a length necessary for the construction of the bridge. At this time, the bridge girder 100x can be connected and manufactured only by the prestressed steel girders 100, 200 and 200 '. However, as shown in Fig. 13A, only the middle of the span where the largest tensile stress acts The prestressed steel girders 100, 200 and 200 'are used, and in other sections, the prestressed steel girders 10 can be used to manufacture the bridge girders 100x.

As shown in Fig. 13B, the bridge girder 100x thus produced is lifted by the crane 80 and is mounted on the lower structure 51 such as a pier or an alternating bridge, and the bridge girder 100x The bottom plate concrete 20 is synthesized on the upper side to form a bridge bottom plate. Then, the packaging surface 30 is installed on the upper surface of the bridge deck and the rail 35 is installed, thus completing the construction of the plate-shaped bridge 101.

Here, the bridge girder 100x having the prestressed steel girders 100, 200, 200 'disposed at the center of the span has a high resistance to tensile stress and compressive stress, while the bottom plate concrete 20 has tensile stress It is possible to form the spiral portion 20a of the bottom plate concrete 20 as high as possible and to construct the bottom plate with a small thickness as shown in FIG. 13D. Thus, by setting the neutral axis NL of the bridge to be located on the upper flange of the bridge girder 100x formed of a steel material or on the upper side thereof, the tensile stress acting on the bridge is supported by the bridge girder 100x can do.

Therefore, conventionally, it is not necessary to excessively form the bottom plate concrete to be thick, so that the construction efficiency of the entire bridge can be improved.

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.

101: Bridge
100, 200, 200 'prestressed steel girders
100x: girder for bridge 10: steel girder
110, 210: first girder 111, 211: upper flange
112, 212: abdomen 120: steel plate
130: Hydraulic jack 140, 240: Lower flange
88: Hinge bolt 90: Wire

Claims (22)

A method of manufacturing a steel girder for a bridge,
Preparing a first girder formed of a steel material, the first girder including a " ull " -shaped section of a first flange and an abdomen forming a lower flange;
Wherein the steel plate is fixed at a first position spaced apart from an end of the abdomen, the steel plate fixed at the first position is formed to pass through a central portion in the longitudinal direction of the abdomen, A steel plate installation step in which the steel plate is hinged to the abdomen at the first position, the steel plate being formed to have higher flexural rigidity than the flexural rigidity of the first girder;
Wherein the first flange is inserted into the first flange in a state in which the first flange is held in a posture of a "ㅗ" -shaped section located below the abdomen, while a part of the hydraulic jack is supported by the steel plate, A bending load introducing step of causing a bending deformation in a direction in which a central portion of the first girder is convex upward;
A second flange joining step of joining a second flange forming an upper flange to the abdomen of the first girder in a state in which the first girder is bent, to form a steel girder having an I-shaped cross section;
A bending load removing step of removing a bending load introduced by the hydraulic jack;
A steel plate removing step of removing the steel plate from the abdomen;
Wherein a compressive prestress is introduced into the lower portion of the neutral axis of the first flange and the abdomen, and a tensile prestress is introduced into the second flange above the neutral axis of the abdomen.
The method according to claim 1,
Further comprising a girder supporting step of supporting the girder at a position spaced apart from both ends of the first girder before the bending load introduction step,
And the second flange coupling step is performed in a state where the first girder is supported in the form of an inner bolster.
The method according to claim 1,
Wherein the abdomen is formed in an upwardly convex arch shape in a state in which no flexural deformation is generated.
The method according to claim 1,
Wherein the bending stiffness of the first girder is higher than the bending stiffness of the first girder.
The method according to claim 1,
Wherein the steel plate is installed on both sides of the abdomen.
2. The method of claim 1,
The hydraulic jack installed at both ends of the first girder is installed in either the steel plate or the first flange and the hydraulic jack is pushed against the steel plate to push the first flange. A method of manufacturing a prestressed steel girder.
The method according to claim 1,
Wherein the second flange is larger in cross-section than the first flange.
The method according to claim 1,
Wherein the bending load introducing step is performed while restricting displacement of both end portions of the steel plate.
9. The method according to any one of claims 1 to 8,
Wherein the first position is at two locations spaced from both ends of the abdomen.
10. The method of claim 9,
Wherein the first position is a position spaced apart from both ends of the first girder by L / 5 to 3L / 5 of the length (L) of the first girder.
10. The method of claim 9,
Wherein the first position is a height of a neutral axis of the first girder.
10. The method of claim 9,
Wherein the second flange is formed by bending at a curvature of the abdomen coupled to the first girder.
A prestressed steel girder fabricated according to any one of claims 1 to 8.
14. The method of claim 13,
Wherein the first position is installed at two places spaced apart from both ends of the abdomen.
A girder for a bridge which is mounted on the bridge substructure including the steel girder according to claim 13;
A bottom plate concrete synthesized on the upper side of the steel girder;
Including the bridge.
16. The method of claim 15,
Wherein the bridge girder is constituted by connecting a plurality of segment girders in the longitudinal direction, and the steel girder is disposed at a central portion of a section of the girder of the bridge acting on the moment.
17. The method of claim 16,
The bottom plate concrete is formed to include a tapered portion above the upper flange of the bridge girder, and the neutral axis of the composite section of the bridge girder and the bottom plate concrete is located above the bridge girder Bridge.

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