KR102451810B1 - steel girder bridge of slab concrete section used as compression member and progreprestressed - Google Patents

Abstract

The present invention removes the steel plate of the upper flange of the conventional steel composite girder produced with an “I” cross-section and produces a “ㅗ” cross-section, then replaces the removed upper flange compression member with concrete, but assembles it on the After pouring concrete and integrating it, remove the copper bar, load the common load, and apply tension in stages to increase the efficiency of the lower flange steel material by applying the tension force step by step. It can fundamentally prevent construction defects and fall accidents due to work at height, and also can contribute to shortening the construction period as it is possible to manufacture the upper structure separately from the bridge pier work.

Description

A steel girder bridge using concrete to introduce tension in stages as a compression member of the upper flange {steel girder bridge of slab concrete section used as compression member and progreprestressed}

The present invention relates to an "I" type steel composite girder formed by synthesizing the upper flange with concrete after manufacturing a steel material having a cross section of "ㅗ", and in particular, using the concrete disposed on the upper flange of the girder as a compression member, , It relates to a method of constructing a steel composite girder that improves the efficiency of steel materials by carrying out tension work step by step.

Steel is a member that is stronger in tension than compression. Therefore, it is widely used in tensile parts in the form of steel plates and reinforcing bars in bridges. A steel composite girder using a steel plate generally has an “I”-shaped cross section. The steel plate of the lower flange responds to the tensile force, and the steel plate of the upper flange responds to the compressive force. However, expensive steel is used as the compression member. In addition, the prior art has many disadvantages, such as fall accidents, poor workability, and construction period, by installing formwork and copper bars on the top of the upper flange and then pouring slab concrete, so it is necessary to improve them. There is this.

The present invention was devised to solve the above problems, and instead of the steel plate of the upper flange that was responsible for the compressive force of the steel composite girder, concrete is used as a compression member, and the amount of steel is reduced by tensioning step by step, and the slab is integrated with the girder. The purpose of this is to improve safety and constructability and shorten the construction period by eliminating slab work in the high-altitude area.

The present invention for achieving the above object is to remove the steel plate of the upper flange of the conventional steel composite girder produced with an “I”-shaped cross-section to produce a “ㅗ”-shaped cross-section, and then convert the removed upper flange compression member into concrete. However, after assembling on the copper bar and pouring concrete to integrate it, remove the copper bar, apply a common load, and apply tension in stages so that the concrete takes on the compressive force, increasing the efficiency of the lower flange steel material. We aim to provide an economical and safe steel girder construction method.

As described above, in the steel composite girder bridge in which the slab is integrated according to the present invention, the slab concrete to be poured does not act only as a dead load, but utilizes it to take charge of the compressive force. Therefore, it is possible to reduce the amount of steel by eliminating the upper flange steel plate. In addition, it is possible to further reduce steel materials by optimizing the cross section by introducing a tension force to the lower flange. As a slab-integrated girder, it is possible to fundamentally prevent construction defects and fall accidents due to work at height. In addition, it is possible to manufacture the upper structure separately from the bridge pier work, which can contribute to shortening the construction period.

1 is a cross-sectional view illustrating a conventional rigid composite girder.
Figure 2 is a cross-sectional view illustrating a rigid girder of the present invention.
3 to 12 are side and cross-sectional views explaining the "construction method for applying prestress step by step" of the present invention.
Figure 3 is a one-step process of the present invention, a side view of a steel girder having a cross-section "ㅗ" type.
Figure 4 is a two-step process of the present invention, a side view of the "ㅗ" type steel girder assembled thereon after installing the dongbari.
Figure 5 is a three-step process of the present invention, a side view of the appearance of installing the dongbari and formwork on the "ㅗ" type steel girder and pouring the upper concrete.
Figure 6 is a side view of a state in which the first prestress is introduced by removing the dongbari as a four-step process of the present invention.
7 is a side view of a state in which a second prestress is introduced by loading a common load on the upper concrete in a five-step process of the present invention;
Figure 8 is a 6-step process of the present invention, a side view of the process of confining the prestress after the secondary tension force is introduced to some extent in the girder under the common load.
9 and 10 are side and cross-sectional views of the seven-step process of the present invention, in which the "I" type steel composite girder is mounted on the pier and then bound to each other in the transverse direction.
11 and 12 are the eight-step process of the present invention, as another embodiment of the present invention, after mounting the "I" type steel composite girder on the pier, the side and cross-sectional views of pouring slab concrete thereon.
Figure 13 is a 9-step process of the present invention, a side view and a cross-sectional view of a state in which the steel wire is added to the "I" type steel composite girder to introduce prestress step by step.
14 is a stress diagram that occurs in a continuous bridge.
Figure 15 is an explanatory view for explaining the tension force introduction process of the conventional rigid composite girder preflex (Preflex) bridge.

The present invention will be described in detail with reference to exemplary drawings. However, since it can be implemented in several different forms, the technical scope is not limited to the embodiment described here. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description will be omitted to help understanding.

1 is a cross-sectional view illustrating a conventional steel composite girder, and shows that the conventional steel girder in FIG. 1a forms an "I" shape. First, it is composed of a lower flange 10 in the lower part of the girder, an abdomen 20 in the middle part, and an upper flange 40 and a shear connector 50 in the upper part. The lower flange 10 receives a tensile force, the upper flange 40 receives a compressive force, and the abdomen 20 maintains a distance between the upper flange 40 and the lower flange 10 . Structural principles of beams and girders correspond to universal knowledge, and detailed descriptions will be omitted.

FIG. 1B is a view showing that the lower concrete 60 is poured on the lower flange 10 and the slab 70 is constructed on the upper flange 40 . The lower concrete 60 has the purpose of preventing rust by covering the steel, but is mainly poured to confine the prestress after giving the steel girder a prestress (tension: Prestress). Prestress is a process in which a load is applied to a steel material to introduce stress into the interior, and is used in the same sense as “tension force”. In the future, the representative prestress bridge, the Preflex girder, will be described in detail as an example. The shear connecting material 50 is located on the upper flange 40, and is used in various forms such as stud bolts, hook reinforcing bars, and serves to connect the girder and the slab 70, and in the present invention, in the form of a stud bolt. indicate 1c shows the abdomen 20 and the upper flange 40 also covered by pouring concrete, and most steel girder bridges are completed in this form in consideration of usability.

Figure 2 is a figure for explaining the girder of the present invention, as in Figure 2a is composed of a lower flange (10), an abdomen (20), a shear connector (50), there is no upper flange (40). Without the upper flange 40, the girder cannot respond to the compressive force generated when a load is applied, and the girder is broken. Figure 2b shows that this compression member is replaced with the upper concrete (30). Concrete is an excellent compression member and can reduce the construction cost by replacing the expensive upper flange 40 steel.

However, the method of replacing the upper flange 40 with concrete in this way is a previously disclosed technology, and the present invention does not claim an alternative method, but first describes the shape of the girder used in the present invention. That is, it stipulates that the present invention is an applicable subject.

Here, referring to FIG. 2a, it is composed of a lower flange 10, an abdomen 20, and a shear connector 50 made of a steel material, and thus has a “ㅗ” shape. Of course, it becomes a girder that can function properly only by pouring the upper concrete 30 as shown in FIG. 2B. For convenience, the girder of the present invention shown in Fig. 2b will be referred to as an "I" type steel composite girder 100. Figure 2c is a graphical perspective view to make it easier to understand Figure 2b.

3 to 12 describe a construction method for applying a prestress step by step as the main content of the present invention.

Figure 3 is a one-step process of the present invention, the cross section of the "ㅗ" type steel girder is a figure viewed from the side, showing that a certain part of the camber is produced. Most prestressed girders are built with a camber. This is to correct in advance the deflection caused by the applied load. The reason for giving the prestress is to be omitted as a general knowledge for the purpose of reducing the amount of steel by using the steel of the lower flange 10 more efficiently.

Figure 4 is a two-step process of the present invention, after installing the dongbari 80, it is a view of assembling a "ㅗ" type steel girder thereon. As it is assembled so that the middle rises upward (camber), no force is applied inside the girder and there is no stress generated inside the girder while it is placed on the ridge 80. That is, it is in a non-stress state.

Figure 5 is a three-step process of the present invention, a state in which the "ㅗ" type steel girder is installed with the copper bar 80 and the formwork and the upper concrete 30 is poured. However, since the girder weight and the load of the upper concrete 30 are supported by the girder 80, no force acts inside the girder and there is no stress generation. That is, it is in a non-stress state. Preferably, high-strength concrete is poured. Thus, the "I" type steel composite girder 100, which is a girder type used in the present invention, was manufactured.

Figure 6 is a four-step process of the present invention, a state in which the dongbari (80) is removed. As the copper bar 80 that supported the load disappears, the weight of the girder and the load of the upper concrete 30 act on the "I" type steel composite girder 100, and stress is generated inside the girder. Tensile stress is generated in the lower flange 10 and compressive stress is generated in the upper concrete 30 . The tensile stress of the lower flange 10 is dealt with by arranging a thick steel plate, and the upper concrete 30 corresponds to the compressive stress generated at the upper part. Conventionally, as shown in FIG. 1, a thick steel plate was disposed to respond. In other words, it is possible to reduce steel materials by replacing steel plates with concrete.

If the fourth step process is performed using the "I" type steel composite girder 100 having such a function, prestress can be applied by its own load. This is the first tension introduction process. To prestress the steel girder, a large compressor, large hydraulic pressure, and a lot of manpower and time are required. However, in the present invention, the prestress can be simply applied by disassembling the dongbari (80).

7 is a five-step process of the present invention, a state in which a common load is loaded on the upper concrete 30 in a superposed manner. This is the second tension introduction process. The loading method can be easily loaded with a heavy object 90 such as a concrete block or a bucket. The common load refers to the vehicle load when using the bridge, and the load generated by the bridge is largely divided into the girder self-load, slab load, and common load. Accordingly, all the loads that can be applied when using the bridge were loaded, and the corresponding stress was introduced to the lower flange 10 and the upper concrete 30 .

8 is a 6-step process of the present invention, a process of confining the prestress after the secondary tension force is introduced to a certain extent in the girder under the common load. By pouring the lower concrete 60 around the lower flange 10 to restrain the tensioned lower flange 10 member with the lower concrete 60, the tension force introduction process can be completed. If the lower concrete 60 is not poured, the girder will return to the rising state with restoring force when the load is removed. In addition, the lower concrete 60 has a purpose of preventing the occurrence of vibration. A detailed description thereof will be omitted as general knowledge.

That is, in the present invention, the prestress is introduced separately. Prestress introduction should be carried out as much as possible in order to prevent various problems such as deformation of steel girder, occurrence of undue stress, cracks in concrete, and torsion of the abdomen. Rather than applying the load all at once, it should be applied in small steps and in a structural situation where the structure can converge.

The present invention is characterized in that the total two-step tension force introduction method is sequentially applied, but the self-weight and the overload method are used. In the self-weight introduction method, prestress can be introduced simply by removing the moving bar, and in the superimposed load method, prestress can be introduced simply by placing a heavy object in a wide space. This series of prestress introduction process is simple and can prevent deformation of steel girder. In addition, when the applicable object is the "I" type steel composite girder 100, it is possible to reduce the steel material.

9 and 10 are the seven-step process of the present invention, FIG. 9 is a side view after mounting the "I" type steel composite girder 100 on the pier, and FIG. As for the binding method, various methods are possible, such as concrete pouring after connecting reinforcing bars, and binding after tensioning the steel wire, so the description will be omitted. The bridge construction was completed by mounting the "I" type steel composite girder 100 on the pier. This is because the upper concrete 30, which is a compression member, serves as the bridge slab 70. There is no need to cast slabs in the air with the viewing bar. In other words, it is possible to prevent fall accidents and eliminate construction inconvenience.

The slab concrete that needs to be poured is used as a compression member for the girder. The conventional girder of FIG. 1 arranges a steel plate as a compression member on the girder upper flange 40, and pours the slab 70 concrete so that the slab concrete acts only as a dead load. You cannot enjoy the effect of reducing steel.

In addition, the construction period can be shortened by performing lower foundation work such as piers in parallel with the "I" type steel composite girder 100 manufacturing work. Conventionally, after the foundation work, the girder lifting and the slab work are in progress, but in the present invention, the slab work time is omitted. Slab working time is dangerous and takes a lot of time, which is a big advantage.

11 and 12 are the eight-step process of the present invention, as another embodiment of the present invention, after mounting the "I" type steel composite girder 100 on the pier, the slab 70 concrete is poured thereon to be. That is, the slab 70 is additionally constructed on the upper concrete 30 . When the concrete of the slab 70 deteriorates and is replaced, as shown in FIG. 9 , the slab integrated girder may collapse due to the removal of the compression member of the girder when the slab is dismantled.

Therefore, in terms of maintenance, the 8-step process of additionally constructing the slab on the girder may be more advantageous than reducing the construction cost. In other words, the public method should be usable for various purposes. In that aspect, the step-by-step prestress method of the present invention is applied, but there are two methods of using the "I" type steel composite girder 100.

The reinforcing bars disposed in the slab 70 , the upper concrete 30 , and the lower concrete 60 are not shown. Also, it will be omitted in the future. In describing the present invention, parts that are not important and can be understood in general are omitted to help understanding of important technologies.

13 is a 9-step process of the present invention, and shows a state in which an additional function is achieved by additionally disposing a steel wire 110 in the "I" type steel composite girder 100 for introducing prestress step by step. When the lower concrete 60 is poured into the lower flange 10, the steel wire 110 is buried, and after the pre-stress is introduced into the "I" type steel composite girder 100 step by step, additional tension work is performed. Steel wire is a tensile member that can handle high tensile force and is widely used in all bridges such as concrete bridges, steel bridges, and composite bridges. However, this generalized steel wire tensioning technology is also recognized as another patented technology and is being created according to which structure it is applied. Currently, most of the patented bridges have their own patented technology, and another patent claim is secured by adding the steel wire tension technology to the original technology.

It can be said that the tension of the steel wire makes the unique patented technology useful. There are so many examples that it is difficult to list them. A typical example is the RePreflex girder, in which steel wire is additionally placed on the lower flange of the Preflex girder. The addition of steel wire has the effect of reducing the steel material of the lower flange of the preflex girder, and it is recognized as another technology.

In this way, it is intended to create another more useful technology by adding the steel wire tensioning technology to the inherent technology of step-by-step tension of the present invention. In the present invention as well, by arranging steel wires in each section where tensile force is applied in a continuous bridge, it is intended to construct a more efficient bridge such as steel material reduction.

Section A-A explains that the steel plate of the lower flange 10, which is the tensile side, is thickly disposed in the positive moment section of the continuous bridge, but the steel wire 110 can be additionally disposed around the lower flange 10 to make the steel plate thin. In section B-B, tensile stress is generated at the upper end at the point of the continuous bridge, and cracks occur in the slab (70). It explains how to prevent cracking in response to tensile stress by arranging and tensioning the steel wire 110 in the upper concrete 30 to connect the girders to each other. In this way, the addition of steel wire makes the unique technology more useful.

As shown in the stress diagram of the continuous bridge in FIG. 14 , the steel wire 110 is required to be placed under the girder in the positive moment section (+), and the steel wire 110 must be placed in the upper part of the girder in the section (-) negative moment. Therefore, when the lower concrete 60 is poured around the lower flange 10, the steel wire 110 is tensioned to cancel the positive moment, and the steel wire 110 is placed in the upper concrete 30 to cancel the negative moment by tensioning it. do. When using the additional arrangement of the steel wire 110, it is possible to further reduce the steel plate. In addition, a maintenance steel wire capable of additional tension when insufficient tensile force of the lower flange 10, sagging, etc. occurs due to the aging of the bridge is also arranged.

15 is a process of introducing tension of a preflex bridge, which is the most representative among bridges that introduce prestress among conventional steel composite girder (a girder synthesized from steel and other materials, generally using a method of combining steel and concrete). The reason for applying prestress while undergoing a very complicated process is to reduce the amount of steel by maximizing the efficiency of the steel by raising the steel to the ultimate strength. Prevents vibration and improves usability. However, as shown in the figure, such an effect can only be achieved by performing complex processes such as a huge workbench fixing the steel girder, large equipment (compressor, hydraulic jack), rotating work, and a lot of manpower and work time. Therefore, there is an urgent need for a construction method that can perform tension work more easily.

The present invention is characterized in that it uses its own weight and overload method to improve these disadvantages. Self-weight only needs to remove the dongbari (80), the surplus load only needs to raise the weight (90). It is so easy and simple that it is difficult to explain it as a construction method. I think the patenting method should be so simple like this. That will prove to be effective. In addition, only when both the first tension force and the second tension method are performed, all loads that can occur during bridge construction, such as girder weight, slab load, and common load, are introduced as prestresses. By introducing only a part, it cannot perform its function properly. In the step-by-step tension work of the present invention, all loads are converged.

In addition, the object is characterized in that the "I"-type rigid composite girder (100). Conventional girder, as in the case of preflex girder, most of the steel plate is disposed on the upper flange (40). In the present invention, all of the first and second tensioning methods must be performed, but the applicable object is limited to the "I" type steel composite girder (100). There are no claims for other objects. The reason for limiting the target range by itself in this way is that it is the most suitable girder when introducing the step-by-step prestress of the present invention. This is because it has the condensed advantages of reducing steel materials, preventing deformation, shortening time and space, preventing falls, and shortening construction period.

10: lower flange
20: abdomen
30: upper concrete
40: upper flange
50: shear connector
60: lower concrete
70: slab
80: Dongbari
90: heavy
100: "I" type steel composite girder
110: liner

Claims (3)

In a steel composite girder whose cross section is “I” shape, which is synthesized by pouring the upper concrete 30 on the upper end of the steel girder having a “ㅗ” cross-section,
Stage 1; The process of producing a steel girder with a “ㅗ”-shaped cross-section by soaring upward, step 2; The process of installing the copper bar (80) and assembling a steel girder having a “ㅗ”-shaped cross-section thereon, step 3; The process of producing an “I”-shaped steel composite girder by continuously pouring and curing the upper concrete 30 horizontally on the upper part of the “ㅗ”-shaped cross-section of the steel girder abdomen 20, step 4; The process of introducing the first prestress (Prestress) to the steel material of the lower flange 10 and the upper concrete 30 by removing the copper bar 80, step 5; After the first prestress is converged, a common load is applied with a weight 90 on the upper concrete 30 to introduce a second prestress to the steel of the lower flange 10 and the upper concrete 30 , Step 6: Assembling reinforcing bars around the lower flange and pouring the lower concrete (60) to confine and fix the tension, Step 7: “I”-shaped steel composite girder to abutments and piers, Step 8: “ The process of composing the slab 70 by mutually combining the steel composite girder of the I” shape: Compositing by pouring the upper concrete at the upper end of the steel girder having the “ㅗ” shape in cross section, in which prestress is introduced step by step, characterized in that A method of constructing an “I” type rigid girder. In a steel composite girder whose cross section is “I” shape, which is synthesized by pouring the upper concrete 30 on the upper end of the steel girder having a “ㅗ” cross-section,
Stage 1; The process of producing a steel girder with a “ㅗ”-shaped cross-section by soaring upward, step 2; The process of installing the copper bar (80) and assembling a steel girder having a “ㅗ”-shaped cross-section thereon, step 3; The process of producing an “I”-shaped steel composite girder by continuously pouring and curing the upper concrete 30 horizontally on the upper part of the “ㅗ”-shaped cross-section of the steel girder abdomen 20, step 4; The process of introducing the first prestress (Prestress) to the steel material of the lower flange 10 and the upper concrete 30 by removing the copper bar 80, step 5; After the first prestress is converged, a common load is applied with a weight 90 on the upper concrete 30 to introduce a second prestress to the steel of the lower flange 10 and the upper concrete 30 , Step 6: Assembling reinforcing bars around the lower flange and pouring the lower concrete (60) to confine and fix the tension, Step 7: “I”-shaped steel composite girder to abutments and piers, Step 8: “ The process of pouring concrete of the slab 70 on the steel composite girder of the I” shape: A composite “ How to construct an I” type rigid composite girder. The method according to claim 1 or 2,
When the lower concrete 60 surrounding the lower flange 10 is poured, the steel wire 110 is pre-arranged to become tense when the lower concrete 60 is cured, and the steel wire 110 to the upper concrete 30 in the negative moment section at the point. Pre-positioning and tensioning: A method of constructing an “I” shape steel composite girder synthesized by pouring the upper concrete on the upper part of a steel girder with a “ㅗ” cross-section, which is introduced step by step, characterized by .

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