KR20090074452A - Strengthen guarder assembly having closed section - Google Patents

Abstract

A steel girder assembly having the closed cross-section is provided to improve constructability, safety and economical efficiency by improving the structure of the steel. A steel girder assembly having the closed cross-section is composed of a steel girder assembly(20,21) having a closed cross-section, an upper flange(22,25), a lower flange(23,26) arranged under the upper flange, and a pair of web flanges(24,27) connecting the upper and lower flanges. The upper and lower flanges are formed in one or by welding plates. The web flange is composed of a first flange and a second flange whose upper parts are connected to the lower part of the upper flange, and lower parts are connected to the lower part of the lower flange.

Description

Rigid girder assembly with closed cross section {STRENGTHEN GUARDER ASSEMBLY HAVING CLOSED SECTION}

The present invention relates to a rigid girder assembly, and more particularly, to a rigid girder assembly capable of improving safety, economy, and strength by constructing a closed cross section by improving the structure.

In general, steel girders are used in buildings and structures to support high loads. Such steel girders may be classified into H-beams or I-beams according to the cross-sectional shape.

In particular, the H-beams consist of upper and lower flanges 2 and 3 and an abdominal flange 4 connecting the upper and lower flanges 2 and 3, as shown in FIG.

Since the H-shaped steel 1 is manufactured in a factory where processes are standardized, standard specifications are determined. Therefore, in case of using the standardized H-shaped steel (1), the process of cutting the steel plate and welding between the upper and lower flanges and the abdominal flange, which is required when manufacturing the normal girder, is excluded, so that the quality control is easy and the processing cost is reduced. And structural members such as cross beams.

Such H-beams may be applied to bridges, as shown in FIG. As shown, a plurality of H-beams 7 are supported at the bottom of the bridge 6. In addition, the plurality of H-beams 7 may be connected to each other by the connecting member 8 and the bolt (9).

However, the conventional H-shaped steel has been used as a skeleton structural member of the building or a temporary barrier member of the building rather than a road structure such as a bridge because the standard specifications are determined and the section performance is limited due to the limitation of the specification.

That is, the conventional H-shaped steel has a problem that can not be used for road bridges and long span bridges that have a large load due to limited manufacturing specifications despite advantages in terms of production cost reduction and quality control.

In addition, in case of H-type steel bridge, which is limitedly used for road bridges, the number of molds is designed as a variable, ignoring the height of the girder which is a design variable when designing an I-type girder bridge, and the number of molds is excessively increased, which may cause various problems.

In addition, since the number of molds is increased to support the load, the horizontal cross beam and the connecting member are required in large quantities, and a lot of the teaching device is required, resulting in deterioration in workability and economic efficiency.

In addition, since the cross section of the H-shaped steel has a constant width of the upper and lower flanges, the flange width does not increase as the height of the mold increases, which is vulnerable to buckling and decreases the resistance to torsion.

Therefore, the present invention has been made to solve the conventional problems as described above, the object of the present invention is to provide a steel girders that can improve the workability, safety, and economics by improving the structure of the section steel.

Accordingly, the present invention is a preferred embodiment of the present invention to solve the conventional problems as described above the upper flange; A lower flange disposed a predetermined distance away from the lower portion of the upper flange; And a pair of abdominal flanges connected between the upper and lower flanges to connect the upper and lower flanges to each other.

In addition, the present invention includes a first rigid girder consisting of an upper flange and a lower flange arranged to correspond to each other, and an abdominal flange connecting the upper and lower flanges to each other; And a second rigid girder comprising an upper and a lower flange and an abdominal flange connecting the upper and lower flanges to each other, wherein the rigid girder is integrally formed by connecting the upper and lower flanges of the first and second rigid girders, respectively. Provide an assembly.

The present invention provides a rigid girder assembly in which the upper and lower flanges and the abdominal flanges are integrally formed or separately provided and connected by welding.

The present invention provides a rigid girder assembly having a joint plate on the upper and lower flanges and an abdominal flange and fastening the joint plate by bolts and nuts.

The present invention provides a rigid girder assembly in which the upper and lower flanges and the ventral flanges are drilled, and the joint plate is drilled, and then the nuts or bolts are pre-fixed and assembled by assembling the bolts or nuts.

According to the present invention, before connecting the first rigid girder and the second rigid girder, a load is generated in advance on the one side of the upper and lower flanges of each of the first and second rigid girders from the outside of the cross section to generate a sectional force. It provides a rigid girder assembly that can reduce the cross-sectional force by connecting the first and second rigid girders, and then releasing the load.

As described above, the rigid girder according to the preferred embodiment of the present invention has the following advantages.

First, the composite girder according to the present invention is to use the H-shaped steel material by the rolling method as it is to form a rectangular closed cross section that must be configured by the cutting of the steel sheet and the welding of the upper and lower flanges and the abdominal flange of the existing steel girder manufacturing process. Therefore, there is an advantage in that a steel girders having an improved cross section than H-shaped steels can be manufactured by only a single longitudinal welding without undergoing a separate steel bridge fabrication process.

Second, by removing the load in advance in order to remove the stress that may occur at the connection part of the steel girders, the cross-section force in the opposite direction due to the working load acting on the steel girders is generated to reduce the generated stresses, thereby reducing the stress and safety of the steel girders. There is an advantage to improve.

Third, by improving the structure by using the existing H-shaped steel, the performance and economical efficiency of the structure is improved, the construction is convenient, and the high cost of the steel bridge manufacturing process generated in the bridge using the steel girders by the existing steel bridge manufacturing method as a member, There is an advantage that can solve the problem of deterioration.

Hereinafter, with reference to the accompanying drawings will be described in detail a rigid girders according to a preferred embodiment of the present invention.

Figure 3 is a side view showing the structure of a rigid girder according to a preferred embodiment of the present invention.

As shown, the rigid girder 20, 21 proposed by the present invention is the upper flange (22, 25), and the lower flange (23, 26) disposed at a predetermined distance from the lower portion of the upper flange (22, 25) And a pair of abdominal flanges 24, 27 connecting the upper and lower flanges 22, 25, 23, 26 to each other.

In the steel girders having such a structure, the upper flanges 22 and 25 may be formed of integral plates, or may be formed by welding different plates with each other.

The lower flanges 23 and 26 may also be formed in the same manner as the upper flanges 22 and 25. That is, it may be made of an integral plate, or by welding different plates to each other.

The abdominal flanges 24 and 27 are arranged in pairs between the upper and lower flanges 22, 25, 23 and 26. That is, the abdominal flanges 24 and 27 are formed of the first flange 24 and the second flanges 27 which are spaced apart from each other, and the upper part of the first and second flanges 24 and 27 is an upper flange. It is connected to the lower surface of the 22, 25, the lower portion is connected to the upper surface of the lower flange (23, 26).

The steel girders 20 and 21 having such a structure have the upper and lower flanges 22, 25, 23 and 26 connected in the lateral direction and have a closed rectangular cross section at the I-shaped cross section.

Therefore, when a load is applied to the steel girders 20 and 21 having such a closed cross-sectional structure, the bending stiffness of the steel shaft is twice the cross section of the H-shaped steel, the stiffness of the weak shaft is greatly increased, and the torsional rigidity is also increased. Performance is improved.

As a result, the above-mentioned steel girders 20 and 21 can increase the performance by synthesizing each mold into one without increasing the number of molds, and thus, various supporting members and supporting devices generated when supporting loads using H-beams as girders. It can reduce the use of such.

The girder 20, 21 may be combined integrally by welding or bolting, such as two girders, or may be manufactured by forming a girder consisting of the upper and lower flanges and the abdominal flange by the molding method.

Figure 4 is a side view showing an embodiment of configuring a bridge using a rigid girder according to the present invention.

As shown in the drawing, two sets of rigid girders 20 and 21 are installed at the lower portion of the bridge B to support the structure. The first rigid girders 20 and the second rigid girders 21 are connected to the lower surface of the bridge B, and a connecting plate L is installed therebetween.

Both ends of the connecting plate L are fastened to the first and second steel girders 20 and 21 by bolts 35. At this time, the bolt 35 preferably includes a high tension bolt.

Therefore, since the bridge is supported by the pair of rigid girders 20 and 21, the number of the rigid girders 20 and 21 can be reduced, thereby reducing the number of connecting plates and bolts.

On the other hand, Figure 5 shows an embodiment of increasing the rigidity by using the rigid girders according to the present invention.

As shown in Fig. 5 (a), the rigid girders 20 and 21 provided in the present invention drill holes by the number of bolts required for the upper flange 22 and the lower flange 23. Of course, the abdominal flange 24 is also drilled.

Then, as shown in Figure 5 (b), after drilling the rigid girders (20, 21), the nut (N) is fixed to the drilling position. At this time, the method of fixing the nut (N) is possible in a variety of ways, but preferably fixed in advance around the perforation by tag welding.

And the joint plate 39 is provided in the outer surface of the upper and lower flanges 22 and 23, and the outer surface of the abdominal flange 24, respectively. At this time, holes are also formed in the joint plate 39, and the holes are assembled so as to coincide with the perforations of the upper and lower flanges 22 and 23 and the abdominal flange 24.

As shown in Fig. 5 (c), after the joint plates 39 are installed on the upper and lower flanges 22 and 23, the bolts 41 are aligned at the fastening positions with the perforations.

Then, as shown in Figure 5 (d), by inserting the bolt 41 in the perforation, the bolt 41 passes through the perforation to be fastened to the nut (N).

As described above, when the first rigid girder 20 and the second rigid girder 21 are integrally connected, the upper and lower flanges 22 and 23 may be connected by the joint plate 39.

According to this method, it is possible to assemble the closed section by the joint plate and the high-tension bolt connection method, not welding, so that it is possible to manufacture the girder as required length in the longitudinal direction.

In addition, in the assembling process, the nut is first assembled and then assembled in the order of fastening the bolt, but the present invention is not limited thereto, and the reverse may be assembled.

That is, as shown in Fig. 6A, the number of bolts 41 required for the upper and lower flanges 22 and 23 and the abdominal flange 24 is drilled.

Then, as shown in Figure 6 (b), after drilling the rigid girders (20, 21), the bolt 41 is fixed to the drilling position. After fixing the bolts 41, the joint plates 39 are provided on the outer surfaces of the upper and lower flanges 22 and 23 and the outer surfaces of the abdominal flange 24, respectively. At this time, holes are also formed in the joint plate 39, and the holes are assembled so as to coincide with the perforations of the upper and lower flanges 22 and 23 and the abdominal flange 24.

As shown in Fig. 6 (c), after the joint plates 39 are installed on the upper and lower flanges 22 and 23, the nuts N are aligned at the fastening positions with the perforations.

And, as shown in Figure 6 (d), the nut (N) is to be fastened to the bolt 41 protruding to the outside of the perforation.

On the other hand, as shown in Figures 7 (a) and 7 (b), the steel girders 20, 21 proposed by the present invention is the upper and lower flanges 22, 25, 23, 26; Instead of the structure consisting of, the first and second steel girders 20 and 21 separately manufactured may be manufactured by a method such as welding.

As such, when the first and second rigid girders 20 and 21 are connected to each other to manufacture one rigid girders 20 and 21, the maximum cross-sectional force is generated at the welded portion under load.

Therefore, the cross-sectional force must be lowered to increase the safety at the welded part. To this end, the temporary load is applied to the upper and lower flanges 22, 25, 23, and 26 before the welding work to cause deformation, and then the welding work is completed and the load is applied. To load.

That is, as shown in Fig. 7 (a), before connecting the first rigid girder 20 and the second rigid girder 21, the upper part of each of the first and second rigid girders 20, 21 and The load is generated from the outside of the cross section on one side of the lower flanges 22, 25, 23 and 26 to generate the cross-sectional force.

When such a load is loaded, as shown in Fig. 8A, the first bending moment M1 and the second bending moment M2 are generated. That is, the bending moment is generated only in the flange of the loaded portion, and the opposite side does not occur.

And, as shown in Figure 7 (b), the first and second rigid girders (20, 21) are connected in parallel by welding to remove the load.

At this time, the generated bending moment is opposite to the load loading direction, so that the bending moment in the opposite direction is generated as shown in FIG. 8 (b), and the upper part of the closed rectangular cross section in which the bending moment is not generated by the load of FIG. 7 (a). And the bending moment is also generated in the lower flange (22, 25, 23, 26).

Therefore, the sum of the bending moments shown in Figs. 8A and 8B can form a bending moment diagram as shown in Fig. 9. That is, in the upper and lower flanges 22, 25, 23, and 26, the upper and lower portions of the closing quadrangle remain as much as the bending moment due to the loaded load.

10 shows a case where the working load acts on the rigid girders 20 and 21 proposed by the present invention. As such, when the working load acts on the rigid girders 20 and 21, a bending moment as shown in Fig. 11A is generated. That is, the maximum bending moment occurs at the intermediate portion between the first bending moment M1 and the second bending moment M2.

11 (b) is the sum of the bending moments introduced in the cross section shown in FIG. 9 and the bending moments opposite to each other due to the use load.

That is, as shown in the figure, the member force in the welding is the bending moment generated by the load of Figure 8 (b) and the bending moment generated by the working load are opposite to each other and can be canceled with each other to reduce the final bending moment in the cross section. .

Fig. 12 is a stress diagram showing the variation of the generated stress in the flange cross section through the above process.

12A is a stress diagram at the cross section of a welded portion generated by a load load and a removal process after welding connection. At this time, the upper edge of the flange cross section is tensile and the lower edge is compression.

Fig. 12 (b) is a stress diagram in the cross section of the welded portion generated by the working load. At this time, the upper edge is compression and the lower edge is tensile.

Fig. 12 (c) shows a state in which the two stress lines are summed together. That is, this stress diagram represents the stress state caused by the bending moments in opposite directions in the cross section of the weld, so that the final stress in the cross section is reduced.

1 is a side view showing an H-beam according to the related art.

FIG. 2 is a view showing a state of supporting a bridge by the H-beam shown in FIG.

Figure 3 is a side view showing a rigid girder assembly according to a preferred embodiment of the present invention.

4 is a view showing a state of supporting the bridge by the rigid girder assembly shown in FIG.

5 (a) to 5 (b) are views showing a state in which the connection to the rigid girder assembly shown in Figure 3 by using a joint plate and a bolt sequentially.

6 (a) to 6 (b) are views sequentially showing another embodiment in which the joint plate and the bolt are connected to the rigid girder assembly shown in FIG.

Figure 7 (a) is a view showing a state of loading in a state in which the first and second rigid girders are separated, Figure 7 (b) is a view of loading a state in the first and second rigid girders combined. The figure shows the state.

Fig. 8 (a) is a stress diagram in the state of Fig. 7 (a), and Fig. 8 (b) is a stress diagram in the state of Fig. 7 (b).

Fig. 9 is a stress diagram showing a state in which the bending moments shown in Figs. 8 (a) and 8 (b) are added together.

10 is a view showing a state in which the working load acts in a state in which the first and second rigid girders are connected.

FIG. 11 (a) is a stress diagram showing the maximum bending moment generated at the middle of the first bending moment M1 and the second bending moment M2, and FIG. 11 (b) is introduced in the cross section shown in FIG. This is a stress diagram showing the sum of the bending moments and the bending moments of opposite signs due to the working load.

Fig. 12 (a) is a stress diagram at the cross section of the welded portion generated by the loading and the removal process after welding connection, and Fig. 12 (b) is a stress diagram at the cross section of the welded portion generated by the working load.

Claims (6)

Upper flange; A lower flange disposed a predetermined distance away from the lower portion of the upper flange; And And a pair of abdominal flanges connected between the upper and lower flanges to connect the upper and lower flanges to each other. A first rigid girder comprising upper and lower flanges disposed to correspond to each other, and an abdominal flange connecting the upper and lower flanges to each other; And A second rigid girder comprising upper and lower flanges and an abdominal flange connecting the upper and lower flanges to each other; The rigid girder assembly integrally formed by connecting the upper and lower flanges of the first and second rigid girders, respectively. The rigid girder assembly according to claim 1 or 2, wherein the upper and lower flanges and the abdominal flange are integrally formed or separately provided and connected by welding. The rigid girder assembly according to claim 1 or 2, further comprising a joint plate on the upper and lower flanges and an abdominal flange, and fastening the joint plate by bolts and nuts. The rigid girder assembly according to claim 4, wherein the upper and lower flanges and the abdominal flange are drilled, and the joint plate is drilled, and then the nut or bolt is pre-fixed and assembled by assembling the bolt or nut. The method of claim 2, wherein before connecting the first and second rigid girders, the cross-sectional force is applied by loading a load from the outside of the cross section on one side of the upper and lower flanges of each of the first and second rigid girders. And a girder assembly capable of reducing the cross-sectional force by releasing the load after connecting the first and second rigid girders.

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