KR20200137334A - Advanced Interlocking Girder adapt to Load Factor Resistance Design Method - Google Patents

Abstract

The purpose of the present invention is to devise a new concept of a main girder which is suitable for a limit state design method, thereby enabling the construction of a more economical and durable composite girder bridge. To this end, the main girder constituting the composite girder bridge can have a portion completely surrounded by at least one steel plate, and a compression flange and a web, which are member sections vulnerable to local buckling due to compression and shear, are synthesized with high-strength concrete having a predetermined thickness, thereby greatly increasing flexural and torsional rigidity. As a result, an applicable span of a conventional steel-concrete composite girder is increased, and there is no need to install horizontal and vertical stiffeners respectively arranged on the web and the compression flange of the cross-section of the composite girder, thereby significantly reducing girder manufacturing costs.

Description

Fastening girder with structural performance suitable for limit state design method {Advanced Interlocking Girder adapt to Load Factor Resistance Design Method}

The present invention relates to the fabrication of a housing for a composite girder bridge combined with a concrete deck, and in more detail, the flexural and torsional stiffness is greatly increased by using a steel-concrete composite panel for the compression flange and abdominal member of the housing. And, through this, it is related to the development of a housing suitable for curved bridges or long span bridges by improving the resistance to local buckling of steel plates that are subjected to compressive stress and shear stress respectively or at the same time.

First, the structural characteristics of the composite bridge, which is the background of the present invention, will be briefly described. The composite bridge goes through a construction process in which the housing is first manufactured at the factory or bridge construction site, and then mounted with a crane, and then combined with a concrete deck that directly resists vehicle load. In such a construction process, the housing has an I-shaped cross-sectional shape with high structural resistance to bending so that it can effectively resist not only its own weight but also the sectional force caused by the external load generated during the construction of the floor plate, especially the bending moment. It is common to have).

As shown in Fig. 1, the housing of the conventional composite bridge is often made of type I made of the steel material of Fig. 1(a) or the concrete single material of Fig. 1(b), but the dwelling made of concrete It is no longer advantageous in terms of economics, but as the span increases, the weight of the housing increases sharply, and the use of a large crane is required. On the other hand, the housing made of only steel is light in weight and is easy to install, but it is disadvantageous compared to the housing made of concrete in terms of economical efficiency, and it has a problem that it is difficult to use for curved bridges due to its weak torsional stiffness.

Recently, in order to reduce the weight of the concrete housing, as shown in (c) to (d) of Fig. 1, a mixed type housing using a steel material on the abdomen has been developed, and the preflex composite type shown in Fig. 1 (e) In the case of the girder bridge, a structure that wraps the tension-side steel with concrete is introduced to increase the flexural stiffness of the housing. In addition, as shown in Fig. 1(f), contrary to the preflex, a steel-concrete composite structure has been developed and used in the area subject to compressive stress due to bending. And as shown in Fig.1(g), a girder that surrounds the concrete housing with a thin steel plate along the outer shape of the concrete housing exposed to the outside air, fills the inside of the steel plate with concrete, and then introduces the pre-compression force to the entire composite section using a PS steel wire. The format has also been developed.

As discussed above, housings with various shapes have been developed and used for composite bridges, but most of them have I-shaped cross-sectional shapes, so they have a limitation that they cannot be applied to bridges with a small curved radius in plan.

On the other hand, in a composite girder bridge having a small curved radius in a plane, a box section made of closed-type steel with increased torsional stiffness shown in Fig. 1(h) is mainly used, but such a box section has to undergo a relatively complicated manufacturing process. do. In other words, the horizontal and vertical stiffeners must be arranged to install bulkheads inside the box to maintain the rectangular cross-sectional shape and to prevent the buckling of the steel plate due to compressive and shear forces, so the weight of the steel material is greatly increased compared to the I-shaped housing. In addition, production is also relatively difficult, resulting in poor economic efficiency.

In Korea, the design standard for composite girder bridges has been changed from the Allowable Stress Design Method (ASD) to the Limit State Design Method (LRFD) since 2012, and the stress generated by the working load is less than the allowable stress set at 50 to 60% of the material yield stress. Unlike the allowable stress design method, which makes it equal to, the limit state design method calculates the resistance capability of the section in the extreme state based on the yield stress of the material.

The main characteristic of the composite girder bridge is that the resistance performance of the cross section against bending and torsion is greatly increased when the concrete deck and the housing are combined regardless of the type of housing. Most of the composite girder bridges are constructed with live-load composite girders (semi-composite girders) that withstand both the self-weight of the dwelling alone and the floor plate concrete in an unhardened state due to the simplicity of construction. However, in some cases, in order to lengthen the span and reduce the manufacturing cost of the housing, some of the elements belonging to the concrete floor plate are pre-combined with the housing (partial composite girder), or it is hardened by forming a number of temporary points within the span. After the temporary points are allowed to withstand the self-weight of the unrefined concrete, it is sometimes constructed as a composite girder (total composite girder) for dead load and live load that removes temporary points after curing of the concrete deck is completed.

If the shape, dimensions and materials of the composite girder bridge are the same, the magnitude of the stress generated in the cross section of the housing when a live load (vehicle load) is applied decreases in the order of "semi-composite girder> partial composite girder> total composite girder". In other words, in the allowable stress design method, which limits the amount of material stress constituting the cross section of the housing, it becomes the most economical composite bridge when it is constructed with an entire composite girder. Until now, many bridge engineers have been making efforts to develop the construction method or the cross-sectional shape of the housing section to reduce the amount of stress that occurs in the housing of the composite girder bridge.

However, the limit state design method focuses on securing the ultimate resistance of the cross section of the composite girder, and at the same time, the magnitude of the stress generated in the steel material due to the working load is 80% of the material yield stress in the case of the non-composite state with the concrete deck. In the synthetic state, up to 95% each is allowed.

Figure 2 shows a schematic diagram of the relationship between the load and the deflection curve of a simple supported bridge according to the method of synthesizing with a concrete deck. From Fig. 2, it can be seen that the ultimate resistance of the composite girder is finally the same regardless of the type of construction method. However, it can be seen that the elastic behavior area of the composite girder can be expanded in the order of "full composite girder> partial composite girder> semi-composite girder".

As discussed above, it can be seen that the change in the design standard for the composite girder bridge has a great influence on the cross-sectional shape and construction method of the housing, and the construction methods developed so far mainly determine the magnitude of the stress generated in the working load condition. It was focused on reducing. However, in the limit state design that focuses on securing the resistance capability in the extreme state, rather than the development of a method that can reduce this stress level, it is urgently required to ensure that the entire section of the housing reaches the yield state at the same time in the extreme state. Can be seen.

The most effective way to increase the cross-sectional resistance capacity of a composite girder bridge is to increase the height of the housing. Therefore, in the case of a concrete housing mainly constructed as a simple bridge, reinforcing bars or PS placed in the tensile area due to the bending moment The size of the resistance strength is determined by the amount of steel, and in the case of a steel housing constructed as a simple bridge or a continuous bridge, the size of the compression and tensile flange is a factor that determines the resistance of the section.

However, if the height of the housing is increased, when the abdominal material is made of concrete, the weight of the girder increases rapidly.In the case of steel material, the thin abdominal plate becomes vulnerable to shear buckling, so the thickness of the abdominal plate must be increased more than necessary, or a large amount Problems arise that vertical and horizontal reinforcement plates must be added to the abdominal plate. In addition, when the height of the dwelling is higher, safety problems occur due to the lateral buckling of the girder lifting and the floor plate concrete construction.To prevent this, increase the stiffness of the columnar beams connecting the dwellings and increase the number or torsional stiffness of the dwellings. It is necessary to take measures such as changing the cross-sectional shape to make it possible.

On the other hand, the compression flange in the steel housing girder may lose its resistance long before it reaches the yield stress of the material due to local buckling of the steel plate if the width of the flange is increased to increase the bending resistance. In order to prevent this local buckling phenomenon, the steel sheet constituting the compression flange must be made to have a predetermined thickness or more, or the protruding length of the compression flange must be reduced, but due to this decrease in flexural stiffness, the height of the housing must be increased again.

(warping stress)이 발생하게 되는 이유로 인해 폐합된 박스단면형상이 사용되고 있다. 박스단면을 사용하는 경우에도 비틀림으로 인한 뒤틀림 변형을 무시할 수 있도록 박스 내부에 적절한 보강재의 설치가 필요하며, 압축응력을 받는 플랜지와 전단응력과 압축력을 동시에 받는 복부판의 국부좌굴현상에 대해서도 검토되어야 하는 이유 등으로 인해 I형 단면에 비해 박스단면형상의 주거더 제작비가 크게 늘어난다.Housing used for composite girder bridges mainly use I-shape for securing efficient flexural stiffness and convenience in manufacturing, but when the bridge linearity has a small curved radius on the plane, distortion due to torsional moment As axially large

The closed box cross-section shape is used for the reason that (warping stress) occurs. Even when the box cross-section is used, it is necessary to install an appropriate stiffener inside the box so that the torsion deformation due to torsion can be neglected, and the local buckling phenomenon of the flange subjected to compression stress and the abdominal plate subjected to shear stress and compression force at the same time should be considered. Due to reasons, etc., the cost of manufacturing a box sectional housing is significantly increased compared to the I-shaped section.

In addition, the cross section of the conventional box girder is pre-fabricated as a box-shaped segment in a steel manufacturing plant due to the complicated arrangement of reinforcing materials, and is brought into the bridge construction site, and each segment is then fastened by friction bonding using high-tension bolts. In general, friction joints using high-tension bolts can be effectively used only when the thickness of the steel plate is less than 30mm, and in reality, there are many designs that control the height of the box girder so that the steel plate does not become thicker than this. However, when the length of the bridge span is increased or the radius of the curve is small in the plane, in order not to increase the thickness of the steel plate due to the relatively large bending moment and torsion moment, the height of the box girder must be increased. The local buckling problem simultaneously accompanies the shear and the amount of steel material increases rapidly, resulting in a sharp decline in economic feasibility.

Steel plate connection by field welding is advantageous in terms of modification possibility and material cost reduction compared to friction joint through high-tension bolt fastening, but it is inevitable due to problems such as setting of members for welding, securing proper welding posture, and securing the quality of the welded part. Or they are reluctant. Particularly, full penetration groove welding for connecting steel plates subjected to tensile and compressive stress requires a highly skilled welder, it is easy to cause deformation of the base metal due to welding, and also requires a lot of non-destructive inspection costs for quality verification. There is this. In contrast, fillet welding for compression or tension parallel to the welding axis has the advantage that it is relatively simple and easy to secure quality as long as an appropriate welding posture is secured.Therefore, it is often used in combination with friction joints due to high tension bolts.

In recent years, in Japan and Europe, instead of reducing the number of I-type steel housings used in the bridge section to two, the steel plates that make up the housings are manufactured in segments so that they have a high strength of 30mm or more, and then welded on site. There is a trend that the use of composite girder bridges of the combined type is increasing. These bridges are mainly used in a straight plane with a span length of less than 60m, and have been introduced in the construction of several bridges in Korea, but are not so active now due to problems such as field welding. Therefore, if the steel plate thickness is made to be less than 30mm by improving the cross-sectional shape of the steel housing girder and structural characteristics of the constituent members, and if the steel plates constituting the housing are connected at the bridge construction site only by friction connection and fillet welding using high-tension bolts, the existing Compared to that, a much more economical bridge construction will be possible.

An object of the present invention is to construct a more economical and durable composite girder bridge by devising a new concept housing der suitable for the limit state design method, and to achieve this purpose, several existing composite girder bridges are already used. It is to solve the following technical challenges that dwellers have.

First, to ensure the most economical resistance to extreme conditions required by the limit state design standard, the member elements constituting the housing should have a cross-sectional configuration that can reach the plastic state from the extreme state specified in the design standard. .

Second, it is possible to have sufficient torsional stiffness while having the shape of an open-type I-type housing, thereby increasing the safety against lateral buckling that may occur during transportation and installation of the housing that is assembled with a span length.

Third, in order to prevent the buckling phenomenon due to the shear stress of the abdominal steel plate due to the increase in the height of the housing and the buckling of the compression flange, which is essential to increase the flexural stiffness, the use of a steel plate that is much thicker than the steel plate thickness required to resist the sectional force according to the micro-displacement theory is recommended By suppressing it, it is possible to reduce the manufacturing cost by reducing the strength of the housing.

Fourth, the height of the girder is lower than that of the conventional box girder, which is mainly used for bridges having a curve in a plane, but by improving the cross-sectional resistance against shear and torsion, the amount of steel required for girder manufacturing is rather reduced, and the box cross-section is constructed. By simplifying the fabrication of each member element, it is possible to manufacture more economical housing.

Fifth, the upper flange, the abdominal material, and the lower flange constituting the housing are manufactured in a separate state at the factory, and then brought to the site, and a predetermined cross section with only fillet welding, which is relatively easy to field welding or friction welding using high-tension bolts. It is intended to be able to assemble into shape.

First, in order to maximize the cross-sectional resistance strength in the ultimate limit state required by the limit state design method, it is required to make the housing section a compact section against the cross-sectional force due to all external loads. In particular, it is necessary to reduce the ratio of the flange thickness (t _f ) to the flange width (b _f ) (= b _f / t _f ) in order to become a compression flange of a dense section, but increase the thickness to satisfy these regulations. If you do, not only will the production cost increase due to the increase in the weight of the steel, but even if a dense section is made by using a very thick steel plate to satisfy the relevant design regulations, only welding can be used for the steel plate connection. Very low.

The most effective way to achieve yield strength without increasing the thickness of the steel plate but without causing elastic buckling of the compressed flange and abdominal plate is to synthesize a high-strength concrete of a predetermined thickness on the steel plate through a shear connector. It is to use a synthetic steel plate.

On the other hand, only welding has been mainly used for the connection between the constituent members forming the steel girder. In other words, until now, the cross section of the housing of the composite bridge was only used by welding to resist the horizontal shear stress acting on the joint surfaces of the steel plates constituting the cross section, so it had to be brought to the site as a member unit consisting of the combined cross section at the factory. In addition, in the field, the already completed cross-sectional shape was subjected to a process of joining the members by friction welding or welding by high-tension bolts, so the coupling method and cross-sectional shape were also subject to many restrictions. However, if the cross-sectional components are first fastened with high-tension bolts to form a predetermined cross section, and then these steel sheets are fastened to each other using the high-strength concrete for preventing buckling of the steel sheets, the expensive welding process can be completely omitted.

In general, the elastic modulus of high-strength concrete with a compressive strength of 40 MPa is about 2.9x10 ⁴ MPa, while the elastic modulus of structural steel with a yield stress of 360 MPa is 2.0x10 ⁵ MPa, and the elastic modulus ratio n between the two materials is about 7. . The buckling strength of a steel plate with a simple quadrant is calculated by the following equation.

식(1)

Equation (1)

는 좌굴계수이며 다음 식으로 구해진다.here,

Is the buckling coefficient and is obtained by the following equation.

식(2)

Equation (2)

here,

)와 콘크리트 부분에 의한 좌굴강도

의 합인 다음의 식으로 구해지므로From equation (1), the buckling strength of a plate subjected to compression is proportional to the square of the thickness of the plate when the material properties and width ratio of the plate are determined. The buckling strength of the steel-concrete composite plate is the buckling strength of the steel plate (

) And the buckling strength by the concrete part

It is obtained by the following equation, which is the sum of

식(3)

Equation (3)

If it is assumed that a steel plate with a thickness of 10 mm is reinforced with concrete with a thickness of 100 mm, the buckling strength of the composite plate increases by about 15 times compared to that of the steel plate alone, and this value is the buckling strength when only a steel plate with a thickness of 40 mm is used. Corresponds to. Therefore, when a composite steel sheet is used for a compression flange, it is possible to construct a dense cross-section in which the entire steel sheet constituting the compression flange reaches a yield state without local buckling without increasing the thickness of the steel sheet.

In addition, the compressive and shear buckling strength of the I-shaped girder and box girder abdominal plate is basically obtained from Equation (1), except that the value of the buckling coefficient varies depending on the inclination of the compressive stress acting on the abdominal plate. If a composite plate with a thickness of about 100 mm attached to the abdomen plate is used, it is possible to obtain a dense section that can secure buckling stability in all cases where the required thickness is less than 40 mm when only steel is used for the abdomen plate.

On the other hand, when the I-shaped section is used as a housing, the torsional stiffness is significantly lower than that of the closed section, which can be easily seen through comparison of the torsional stiffness of the three sections shown in FIG. 3. First, the I-shaped section made of only steel plates of width 800mm x height 2000mm x thickness 30mm shown in Fig.3(a), Fig.3(b) is made of concrete with width 800mm x height 2000mm x thickness:flange 250mm, abdomen:100mm Figure 3(c) shows a case where the concrete of width 780 mm x height 1980 mm x thickness: flange 125 mm, abdomen: 60 mm is completely surrounded by a steel plate of 10 mm thickness, and Figure 3 (d) is shown in Figure 3 (c). In the case of, each of the external steel plates is not closed. Table 1 shows the results of obtaining the pure torsional stiffness for these four cases.

From Table 1, it can be seen that the torsional stiffness of the I-shaped girder made only of thin steel plates (Fig. 3(a)) is significantly inferior to the concrete I-shaped girder (Fig. 3(b)) having similar flexural stiffness. On the other hand, the cross-section of Fig. 3(c) surrounding the outside of the concrete with a steel plate having a thickness of 10 mm has a torsional stiffness of about 2%, although the cross-sectional weight is reduced by half compared to the concrete I-shaped girder of Fig. 3(b). It can be seen that it has increased. However, it can be seen that although the concrete is covered with the steel plate, the effect of increasing the torsional stiffness is not so great when the steel plate is not closed. From the above, it can be seen that the torsional stiffness of the girder section can be greatly increased by wrapping the concrete section from the outside with a thin steel material with a thickness of 10 mm completely closed.

Figure 1 is a cross-sectional shape diagram used in a conventional composite girder bridge.
Figure 2 shows the changes in the ultimate strength and deflection curve of the steel-concrete composite girder according to the difference in construction method.
Figure 3 is a cross-sectional shape used in an example for comparing torsional stiffness.
4 is a box-shaped housing according to a first preferred embodiment of the present invention.
5 is a detailed view of a method of joining steel plates constituting a housing according to a preferred embodiment of the present invention
6 is an I-shaped housing according to a second preferred embodiment of the present invention.
7 is a box-shaped housing according to a third preferred embodiment of the present invention.
8 is a box-shaped housing according to a fourth preferred embodiment of the present invention.
9 is a cross-sectional view of an open composite girder bridge according to a fifth preferred embodiment of the present invention
10 is a cross-sectional view of a single box-shaped composite girder bridge according to a sixth embodiment of the present invention.

Next, the present invention will be described in detail with reference to the accompanying drawings showing examples.

4 is a cross-sectional view of a box-shaped girder according to a first preferred embodiment of the present invention. The upper flange steel plate 1 of the box cross-section has a width of about 1/5 to 1/3 of the lower flange steel plate 2 ( Preferably, it has 1/4), and the abdominal material located on both sides of the box section is composed of an lateral abdominal steel plate 3 and an inner abdominal steel plate 4, respectively, and the upper part of the inner abdominal steel plate 4 extends to the center of the cross section It is made to face the inner abdominal steel plate located on the opposite side, and when the steel plate assembly of (1) to (4) is completed, the integrated box cross-section is formed by filling the space inside the box using high-strength filled concrete (5). It is characterized by its main features.

As shown in Fig. 4, in order to secure the integral behavior between the filled concrete 5 and each steel plate 1, 2, 3, 4, a head stud 6 having a diameter of 2.5 times or less the thickness of the abdominal steel plate is used. It is welded at regular intervals across both sides of the steel plate surface. For the connection of the inner abdominal steel plate (4), a friction joint using a high-tension bolt (7) is used.

In addition, in order to secure a synthetic effect with the concrete upper slab, a head stud 8 having a diameter less than 2.5 times the thickness of the upper flange plate is welded to the upper surface of the upper flange steel plate 1. And in order to maintain the shape of the lower flange steel plate 2 subjected to tensile force and prevent shear buckling, a rectangular cross-section steel plate is additionally installed with horizontal stiffeners 9 welded to the upper surface of the lower flange steel plate 2 at regular intervals, and the above A connection plate 10 having a predetermined shape is provided inside the cross section of the box for coupling the horizontal stiffener 9 and the inner abdominal steel plate 4.

On the other hand, the method of fastening between the steel plates may be different depending on the place where the cross section of the box is assembled. In the case of transporting the steel sections to the bridge site in the assembled state in the steel manufacturing plant, the steel plates are connected to each other by welding 11 at the portions where they contact each other as shown in Fig. 5(a).

In the case of conveying and fastening each steel plate to the bridge site in a separate state, as shown in Fig. 5(b), a hole 12 of a predetermined size is pre-installed at a location 30 mm to 40 mm away from the contact portion of each steel plate. After inserting the high tension bolts 7 into these holes, a friction joint is made to tighten the nuts 13 of the high tension bolts 7 with a predetermined torque. On the other hand, instead of using the high-tension bolt 7 and the nut 13, the steel plates may be combined by fillet welding. That is, the upper and lower ends of the outer abdominal steel plate (3) are connected to the upper and lower flange steel plates (1) (2) using high-tension bolts (7) and nuts (13) or fillet welding, respectively, and the inner abdominal steel plate (4) The lower end of the lower flange plate (2) is coupled, and the upper end of the inner abdominal steel plate (4) can be combined with the upper end of the opposite inner abdominal steel plate (4).

The filling time of the rechargeable concrete (5) can vary depending on the site conditions in which the assembled girder is lifted with a crane.If the use of a large-capacity crane is difficult due to the site conditions, the section consisting of only steel is used to reduce the weight of the girder during lifting. After mounting the girder on the bridge, the filled concrete (5) is filled, and when it is easy to use a large-capacity crane, when the assembly of the steel members is completed on the ground, the filled concrete (5) is immediately filled and the girder is completed after curing for a predetermined period of time. It can also be mounted in a form.

6 is a cross-sectional view of an I-shaped girder according to a second preferred embodiment of the present invention, having an upper flange steel plate 1 and a lower flange steel plate 2 having a predetermined width and thickness, respectively, and an I-shaped abdominal member Consists of two outer abdominal steel plates (3) each made of the same shape so as to have portions (3a) bent in a cold state with a curved radius of 150 mm or more at the upper and lower portions, respectively, and assembling the steel plates of (1) to (3) above. The main feature is to improve the flexural stiffness and torsional stiffness of the girder at the same time by filling the abdominal space of the I-shaped section with high-strength filled concrete (5) when completed.

As shown in Fig. 6, for the construction of the filled concrete 5, holes 14 with a diameter of 80 to 100 mm are installed in the center of the upper flange at intervals of 500 mm or less in the length direction of the steel plate, and the length of these holes is 200 mm or less. After inserting the steel pipe (15) of the length center of the steel pipe to the center of the steel plate, they are welded together.

In addition, in order to secure the integral behavior between the filled concrete and each steel plate (1, 2, 3), a head-attached stud (6) having a diameter of 2.5 times or less of the thickness of the abdominal steel plate is uniform across both directions of all inner steel plate surfaces. They are welded at intervals, and in addition to the steel pipe 15, a separate head stud 8 is welded to the upper surface of the upper flange in order to secure a composite action with the concrete of the bottom plate.

The method of fastening between the steel plates 1, 2, 3 and the construction time of the filled concrete 5 may vary according to the site conditions as described in the first embodiment of the present invention, and the implementation method is as described above. It is the same as described. In other words, in the case of transporting the steel sections to the bridge site in an assembled state in a steel manufacturing plant, the portions where the steel plates (1), (2) and (3) abut each other are connected to each other by welding.

In addition, when each steel plate (1) (2) (3) is transported to the bridge site in a separate state and fastened, the high-tension bolts (7) and nuts (13) are used to make friction joints or by fillet welding. .

7 is a cross-sectional view of a box-shaped girder according to a third preferred embodiment of the present invention, having an upper flange steel plate 1 and a lower flange steel plate 2 each having a predetermined width and thickness, and the inside is filled with concrete. It is composed of two long rectangular abdominal members (16), and when the assembly of the above (1), (2) and (16) is completed, it receives compressive force due to the girder weight and the bending moment generated by the construction of the concrete deck. The main feature is that the upper flange steel plate (1) is synthesized with high-strength filled concrete (5).

Figure 7 shows an embodiment of the girder cross section for the case where the upper flange receives a compressive force due to its own weight and the construction of the floor plate, and there is a high tensile strength in the coupling between the abdominal member 16 filled with concrete and the upper flange steel plate 1 Friction joints using bolts are used, and head studs 6 less than 2.5 times the thickness of the steel plate are welded to the upper surface of the upper flange steel plate 1 for a compounding action with the filled concrete 5 at predetermined intervals.

Meanwhile, in order to maintain the shape of the lower flange steel plate 2 under tension and prevent shear buckling, a rectangular cross-section steel plate is additionally installed as a horizontal stiffener 9 welded to the upper surface of the lower flange steel plate 2 at regular intervals. A connection plate 10 having a predetermined shape is provided on the inner side of the abdominal member for coupling the horizontal stiffener 9 and the abdominal member 16.

In addition, the abdominal member 16 is provided with two vertical steel plates in principle, but in the case of a large curved radius in a plane, the steel plate located inside the box may be omitted. In addition, the upper surface of the abdominal member 16 is welded with a head stud 8 for a composite action with the concrete of the bottom plate.

8 is a cross-sectional view of a box-shaped girder according to a fourth preferred embodiment of the present invention, having an upper flange steel plate 1 and a lower flange steel plate 2 each having a predetermined width and thickness, and the inside is filled with concrete. It is composed of two long rectangular abdominal members (16), and when the assembly of the above (1), (2) and (16) is completed, it receives compressive force due to the girder weight and the bending moment generated by the construction of the concrete deck. The main feature is to synthesize the lower flange steel plate (2) into high-strength filled concrete (5).

8 shows an embodiment of a girder cross section for a case in which the lower flange receives a compressive force due to its own weight and the construction of the floor plate, and the abdominal member 16 and the upper flange steel plate 1 and the lower flange steel plate filled with concrete ( 2) Friction joints are made using high-tensile bolts (7), respectively, and the inner surface of the abdominal member (16) and the upper surface of the lower flanged steel sheet (2) are formed with the thickness of the steel sheet for synthesizing with the filled concrete (5). The head studs (6) of 2.5 times or less are welded at predetermined intervals.

In addition, head studs 6 and 8 of a predetermined length are respectively welded as shear connectors on the upper surfaces of the abdominal member 16 and the upper flange steel plate 1 in order to secure a synthetic effect with the concrete base plate. These head studs The diameter of is not more than 2.5 times the thickness of the steel sheet to be welded.

In addition, horizontal stiffeners 9 are welded to the lower surface of the upper flange steel plate 1 at predetermined intervals to connect both abdominal members 16.

The housing of FIGS. 7 to 8 may be manufactured in the following order.

In the case of transporting the steel section to the bridge site in an assembled state in a steel manufacturing plant, the parts where each steel plate (1) (2) and the abdominal member (16) contact each other are connected by welding.

On the other hand, when each steel plate (1) (2) and the abdominal member (16) are transported to the bridge site in a separate state and fastened, the upper part is formed by friction joint or fillet welding using high tension bolts (7) and nuts (13). Combine the flange steel plate and the abdominal material, and combine the lower flange steel plate and the abdominal material.

Then, the upper flange steel plate (1) or the lower flange steel plate (2), which is subjected to compressive force due to the bending moment generated by the construction of the girder weight and the concrete floor plate, is synthesized with high-strength filled concrete (5) to form a box-shaped composite section. do.

Figure 9 shows a method of constructing a composite girder bridge capable of supporting the entire width of the bridge using two I-shaped girders 17 manufactured according to a second preferred embodiment of the present invention. To prevent the occurrence of lateral buckling when constructing the floor plate concrete (18) by mounting the two housings (17) made of the span length of the bridge, a crossbeam (19) with high rigidity is 20m along the span length. Install at intervals within. It is preferable that the crossbeam 19 has a height of 1/3 or more and 1/2 or less of the height of the housing 17.

The housing (17) and the crossbeam (19) are tightened by a friction joint joint by a high-tension bolt (7), and a vertical stiffener having the same height as the housing (on the inside of the housing where the crossbeam (19) is installed) (20) is installed in advance.

Next, for the construction of the floor plate concrete, a floor plate steel plate 21 of a predetermined thickness, which serves as a formwork function, is welded to the upper surface of the housing, and both ends of the steel plate 21 are the floor plate concrete inside the housing. Bending in a cold state so that the radius (R) is more than 150mm for the purpose of adjusting the thickness and, and a plurality of head studs (6) having a diameter of 2.5 times or less of the thickness of the steel plate of the floor plate are prescribed for compounding action with the floor plate concrete. Weld at intervals.

FIG. 10 is a cross-sectional view of a single box-shaped composite girder bridge according to a sixth embodiment of the present invention, in which two inclined dwellings 22 of a long rectangular shape filled with concrete in an inner space formed of steel plate, a dwelling The lower flange steel plate (2) that connects the lower flange of the more (22) to each other, the horizontal stator (23) and the inclined stirrut (24) that connect the upper flange of the housing to each other, and the concrete floor plate The main feature is that it has a bottom plate steel plate 21 that makes the box cross-section.

As for the construction method, the two housing dors (22) are first mounted on the pier or temporary vent using a crane, etc., and then the horizontal and inclined studs (24) and the lower flange steel plate (2) are mounted with high-tension bolts. Or, assembling sequentially through welding, a box-shaped cross section is formed over the entire length of the bridge. At this time, for the lower flange steel plate near the point where the compressive force acts due to the load and live load during the construction of the floor plate, high-strength concrete (5) is filled in advance to form a composite steel plate structure.

Then, for the construction of the concrete floor plate 18, the floor plate steel plate 21 of a predetermined thickness, which also functions as a formwork, is welded to the upper surface of the housing to form a complete closed section with very high torsional rigidity.

The terms used to describe the embodiments of the present invention above are those used to describe the present invention, and are not used to limit the meaning or the scope of the present invention described in the claims.

1: Upper flange steel plate
2: Lower flange steel plate
3: lateral abdominal steel plate
4: medial abdominal steel plate
5: Filled concrete
6,8: Head attached stud
7: High tension bolt
9: horizontal reinforcing plate for reinforcing flanged steel plate
10: connecting plate
11: Welded joint
12: Hole for high tension bolt installation
13: Nut for tightening high tension bolt
14: hole for concrete filling
15: purchased steel pipe
16: Concrete-filled rectangular abdominal material
17: I-type housing with concrete filling
18: concrete floor plate
19: crossbeam
20: vertical stiffener
21: floor plate steel plate
22: Inclined rectangular housing filled with concrete
23: horizontal stutter
24: Inclined Stirut

Claims (12)

In the housing of the box-shaped composite girder bridge that resists external load through the composite action with the concrete deck
The upper flange steel plate of the box section has a width of 1/5 to 1/3 of the lower flange steel plate, and the abdominal steel plates located on both sides of the box section include an lateral abdominal steel plate and an inner abdominal steel plate, respectively,
The upper end of the inner abdominal steel plate extends to the center of the cross-section of the box so as to be combined with the inner abdominal steel plate located on the opposite side, the outer abdominal steel plate is combined with the upper and lower flange steel plates, respectively, and the inner abdominal steel plate is the lower flange steel plate. And the inner abdominal steel plates facing each other with a horizontal stiffener to form a closed box cross-section,
The housing for a composite bridge, characterized in that the space surrounded by the inner closed section, the upper flange steel plate, the outer abdominal steel plate, and the lower flange steel plate is filled with high-strength concrete to form an integral box cross section. The method of claim 1,
A housing for composite bridges, characterized in that head studs are installed on the upper and lower flange steel plates and the inner and outer abdominal steel plates for integral behavior with high-strength concrete. In the housing of the box-shaped composite girder bridge that resists external load through the composite action with the concrete deck
It has an upper flange steel plate and a lower flange steel plate having a predetermined width and thickness, and the abdominal member includes two outer abdominal steel plates manufactured in the same shape each having a portion bent in a cold state with a curved radius of 150 mm or more, respectively, at the upper and lower portions thereof. ,
When the assembly between the upper flange steel plate, the lower flange steel plate, and the outer abdominal steel plate is completed, the abdominal space of the I-shaped section is filled with high-strength filled concrete, thereby simultaneously improving the flexural and torsional stiffness of the girder. For housing more. The method of claim 3,
A housing for a composite bridge, characterized in that a hole with a diameter of 80mm to 100mm is installed in the center of the upper flange steel sheet at predetermined intervals in the length direction of the steel sheet for the construction of filled concrete, and a steel pipe is inserted into the hole. In the housing of the box-shaped composite girder bridge that resists external load through the composite action with the concrete deck
It has an upper flange steel plate and a lower flange steel plate having a predetermined width and thickness, and has a cross-section consisting of two abdominal members surrounded by a long rectangular steel plate filled with concrete,
When the assembly of the upper flange steel plate, the lower flange steel plate, and the abdominal material is completed, the upper flange steel plate or the lower flange steel plate, which is subjected to compressive force by the bending moment generated by the construction of the girder weight and the concrete floor plate, are synthesized with high-strength filled concrete to form a box shape. The housing for a composite bridge, characterized in that to form a composite section. The method of claim 5,
When a compressive force acts on the upper flange steel plate, horizontal stiffeners 9 are welded to the upper surface of the lower flange steel plate at predetermined intervals to connect both abdominal members,
A housing for a composite bridge, characterized in that when a compressive force acts on the lower flange steel plate, horizontal stiffeners (9) are welded to the lower surface of the upper flange steel plate at predetermined intervals to connect both abdominal members. In the method of manufacturing the housing of the box-shaped composite girder bridge that resists external load through the composite action with the concrete deck
(a) transporting the upper and lower flange steel plates and the inner and outer abdominal steel plates to the bridge construction site;
(b) Combine the upper and lower ends of the outer abdominal steel plate to the upper and lower flange steel plates, respectively, the lower end of the inner abdominal steel plate to the lower flange steel plate, and the upper end of the inner abdominal steel plate with the upper end of the opposite inner abdominal steel plate. And, by connecting both sides of the inner abdominal steel plate with a horizontal stiffener to form a closed box cross-section inside; And,
(c) A method of manufacturing a housing for a composite bridge, characterized in that the space surrounded by the inner closed section, the upper flange steel plate, the outer abdominal steel plate, and the lower flange steel plate is filled with high-strength concrete to form an integral box section. In the method of manufacturing a housing for a box-shaped composite girder bridge that resists external load through a composite action with a concrete deck,
(a) transporting the upper and lower flange steel plates and the outer abdominal steel plates to the bridge construction site;
(b) coupling the upper and lower ends of the two outer abdominal steel plates to the upper and lower flange steel plates; And,
(c) A method of manufacturing a housing for a composite bridge, characterized in that the space surrounded by two outer abdominal steel plates and upper and lower flange steel plates is filled with high-strength concrete to form an integral box section. In the method of manufacturing a housing for a box-shaped composite girder bridge that resists external load through a composite action with a concrete deck,
(a) transporting upper and lower flange steel plates and two abdominal members filled with high-strength concrete inside to a bridge construction site; And,
(b) combining the upper flange steel plate and the abdominal member, and combining the lower flange steel plate and the abdominal member;
(c) After step (b), the upper flange steel plate or the lower flange steel plate, which is subjected to compressive force due to the bending moment generated by the construction of the girder weight and the concrete floor plate, are synthesized with high-strength filled concrete to form a box-shaped composite section. A method for manufacturing a housing for a composite bridge, comprising a. The method according to any one of claims 7 to 9,
The method of manufacturing a housing for a composite bridge, characterized in that the combination of step (b) is made of high-tension bolts or fillet welding. In the construction method of an open type composite girder bridge that resists external loads of vehicles, etc. through a composite action with a concrete deck
A crane is used to mount the dwelling deck of Clause 3, which is made with the span length of the target bridge, and to prevent lateral buckling of the dwelling when constructing a concrete deck, the height of the dwelling is not less than 1/3 of the height of the dwelling. Install a crossbeam with an interval of less than 20m in the span direction to connect the two housings to each other.
Next, a floor plate steel plate of a predetermined thickness, which serves as a formwork function when constructing a concrete floor plate, is welded to the upper surface of the floor plate, and both ends of the floor plate steel plate have a predetermined radius for the purpose of controlling the thickness of the floor plate concrete. Construction method of an open composite girder bridge, characterized in that bending in a cold state to have a. In the construction method of a single box-shaped composite girder bridge that resists external load through a composite action with a concrete deck;
Two inclined housings in a long rectangular shape filled with concrete in the inner space formed of steel plates, a lower flange steel plate that connects the lower flanges of the housings to each other, and horizontal and inclined studs that connect the upper flanges of the housings to each other. And, it includes a constituent element of the floor plate steel plate that makes the box cross-section closed during construction of the concrete floor plate;
First, the above housing is mounted on the pier or temporary vent using a crane, and then the horizontal and inclined studs, and the lower flange steel plate are sequentially fastened through high-tension bolts or welding to form a box-shaped cross section over the entire length of the bridge. In this case, the lower flange steel plate near the point where the compressive force acts due to the load and live load during the construction of the floor plate is filled with high-strength concrete in advance to form a composite steel plate structure;
Then, for concrete deck construction, a single box-type composite girder bridge, characterized in that a complete closed section with very high torsional stiffness is formed by welding a floor plate steel plate of a predetermined thickness that serves as a formwork function between the dwellings. Construction method.

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