KR102479053B1 - Girder with variable section - Google Patents

Abstract

The present invention relates to a tapered cross-section girder, which minimizes a structural weaknesses part, comprising: a box girder unit (10) of a square cross section installed in the front; a plate girder unit (20) of an I-shaped cross section installed in the rear; and a transition section unit (100) installed between the box girder unit (10) and the plate girder unit (20).

Description

Tapered section girder {GIRDER WITH VARIABLE SECTION}

The present invention relates to the field of construction technology, and more particularly to tapered girders.

1 shows a conventional tapered girder.

This is the box girder part 10 of square cross section installed at the front, the plate girder part 20 of I-shaped cross section installed at the rear, and the transition section installed between the box girder part 10 and the plate girder part 20. It is composed of (30).

The box girder part 10 with a large section modulus is used at the branch where the bending moment is large, and the plate girder part 20 is used at the central part where the moment is relatively small. (FIG. 2)

Specifically, the box girder portion 10 is composed of an upper plate 11, a lower plate 12, and a pair of side plates 13.

The plate girder part 20 has an upper flange 21 narrower than the upper plate 11, a lower flange 22 narrower than the lower plate 12, a pair of side plates 13 and a height is composed of the same abdominal plate (23).

The transition section 30 is composed of an upper connecting plate 31, a lower connecting plate 32, a pair of side connecting plates 33, a front closing plate 34, and a rear closing plate 35.

On the other hand, a large bending moment does not occur in the transition section 30, but instead, a large shear stress is generated and becomes a structurally weak part, so countermeasures against this are necessary. (FIG. 3)

However, in the case of the conventional tapered girder, as the coupling structure of the side connecting plate 33 and the rear closing plate 35 formed at the rear of the transition section 30 takes an angled bending structure, There was a problem that a large shear stress (113 MPa, 132 MPa) was generated. (FIG. 4)

The reference numerals of the prior art above shall be limited only to the description of the prior art.

The present invention was derived to solve the above problems, and an object of the present invention is to present a tapered girder that can minimize structural weakness by reducing the shear stress generated in the transition section.

In order to solve the above problems, the present invention is a box girder portion 10 of a rectangular cross section installed at the front, a plate girder portion 20 of an I-shaped cross section installed at the rear, the box girder portion 10 and the plate girder portion It includes a transition section 100 installed between (20), and the box girder portion 10 includes an upper plate 11, a lower plate 12, and a pair of side plates 13, and the plate The girder part 20 includes an upper flange 21 narrower than the upper plate 11; a lower flange 22 narrower than the lower plate 12; The pair of side plates 13 and the same height as the abdominal plate 23; including, the transition section 100, the width of the front end is the same as the width of the top plate 11, the width of the rear end is an upper connecting plate 110 having the same width as the upper flange 21 and gradually narrowing from the front to the rear; A lower connection plate 120 having a width at the front end equal to that of the lower plate 12, a width at the rear end equal to that of the lower flange 22, and gradually narrowing from the front to the rear; One installed between the upper connecting plate 110 and the lower connecting plate 120 so that the height is the same as that of the pair of side plates 13 and the abdominal plate 23 and the gap gradually narrows from the front to the rear. a pair of side connecting plates 130; a front closing plate 140 installed between the front ends of the pair of side connecting plates 130; A pair of rear closing plates 150 installed between the rear end of the pair of side connection plates 130 and the front end of the abdominal plate 23; The front end is coupled to the front closing plate 140 so that it has the same height as the abdominal plate 23 and is positioned on the same plane as the abdominal plate 23, and the rear end is attached to the front end of the abdominal plate 23. In addition to combining, a tapered cross-section girder characterized in that it includes a web connecting plate 160 installed between the upper connecting plate 110 and the lower connecting plate 120.

A slit 141 is formed in the core of the front closing plate 140, and the front end of the abdominal connecting plate 160 is the upper region of the slit 141 in the front surface of the front closing plate 140 and It is preferred that it is bonded to the lower region.

The upper edge is coupled to the lower surface of the upper connecting plate 110 so as to be located on the same plane as the abdominal plate 23 and the abdominal connecting plate 160, and the rear edge is the front surface of the front closing plate 140. An upper abdominal reinforcing plate 170 of an upright structure coupled to the upper region of the opening 141; The lower edge is coupled to the upper surface of the lower connecting plate 120 so as to be located on the same plane as the abdominal plate 23 and the abdominal connecting plate 160, and the rear edge is the front surface of the front closing plate 140. It is preferable to further include; a lower abdominal reinforcing plate 180 of an upright structure coupled to the lower region of the opening 141.

An upward concave portion 171 curved concavely toward the rear upper side is formed in the region between the front upper end and the rear lower end of the upper abdominal reinforcing plate 170, and the lower front lower end and rear lower part of the lower abdominal reinforcing plate 180 are formed. It is preferable that a downward concave portion 181 curved concavely toward the rear lower side is formed in the region between the upper ends.

The pair of rear closing plates 150 are preferably formed curved so as to protrude outward.

When the length between the maximum bending moment occurrence point of the box girder portion 10 and the maximum bending moment occurrence point of the plate girder portion 20 is the length of the shear stress generating section, the transition section portion 100 The length is preferably 10 to 15% of the length of the shear stress generating section.

The ratio of the radius of curvature of the rear closing plate 150 to the width of the upper flange 21 is preferably 40 to 48%.

The present invention proposes a tapered girder that can minimize the structural weakness by reducing the shear stress generated in the transition section.

1 is a perspective view of a conventional tapered girder.
2 is a bending moment diagram of a tapered section girder.
3 is a shear force diagram of a tapered section girder.
4 is a structural analysis diagram of a conventional tapered girder.
5 below shows an embodiment of the present invention,
5 is a perspective view of a first embodiment relating to the structure of a transition section;
Figure 6 is a structural analysis diagram of the first embodiment relating to the structure of the transition section.
7 is a perspective view of a second embodiment related to the structure of a transition section;
8 is a structural analysis diagram of a second embodiment related to the structure of a transition section.
9 to 12 are plan views of first to fourth embodiments relating to the length of a transition section;
13 to 16 are structural analysis diagrams of the first to fourth embodiments regarding the length of a transition section.
17 to 20 are plan views of fifth to eighth embodiments relating to the length of a transition section;
21 to 24 are structural analysis diagrams of fifth to eighth embodiments relating to the length of a transition section.
25 to 29 are plan views of the first to fifth embodiments relating to the radius of curvature of the rear closing plate;
30 to 34 are structural analysis views of the first to fifth embodiments relating to the radius of curvature of the rear closing plate.
Fig. 35 is a perspective view of a third embodiment relating to the structure of a transition section;
36 and 37 are structural analysis diagrams of a third embodiment related to the structure of a transition section.
38 is a perspective view of an embodiment of a bridge with tapered girders installed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 5 and below, the present invention basically includes a box girder portion 10 of a rectangular cross section installed at the front, a plate girder portion 20 of an I-shaped cross section installed at the rear, and a box girder portion 10 And it is configured to include a transition section 100 installed between the plate girder portion 20.

The box girder unit 10 includes an upper plate 11, a lower plate 12, and a pair of side plates 13.

The plate girder portion 20 includes an upper flange 21 narrower than the upper plate 11; a lower flange 22 narrower than the lower plate 12; It is configured to include; a pair of side plates 13 and the same height as the abdominal plate 23.

The transition section 100 includes an upper connecting plate 110, a lower connecting plate 120, a pair of lateral connecting plates 130, a front closing plate 140, a pair of rear closing plates 150, and an abdominal connection. It is configured to include a plate 160.

The upper connecting plate 110 has the same width at the front end as the width of the upper plate 11, the same width at the rear end as the width of the upper flange 21, and gradually narrows from the front to the rear.

The lower connecting plate 120 has the same width at the front end as the width of the lower plate 12, the same width at the rear end as the width of the lower flange 22, and gradually narrows from the front to the rear.

The side connecting plate 130 has the same height as the pair of side plates 13 and the abdominal plate 23, and the upper connecting plate 110 and the lower connecting plate 120 have a gap gradually narrowing from the front to the rear. A pair is installed between

The front closing plate 140 is installed between the front ends of the pair of side connecting plates 130.

A pair of rear closing plates 150 are installed between the rear end of the pair of side connecting plates 130 and the front end of the abdominal plate 23.

The abdominal connecting plate 160 has the same height as the abdominal plate 23, and the front end is coupled to the front closing plate 140 so as to be located on the same plane as the abdominal plate 23, and the rear end of the abdominal plate 23. In addition to being coupled to the front end, it is installed between the upper connecting plate 110 and the lower connecting plate 120.

That is, the tapered girder according to the present invention is characterized in that the web connecting plate 160 is additionally installed compared to the above-mentioned prior art.

This is an addition of a configuration corresponding to the web plate 23 of the plate girder 20 to the transition section 30 of the tapered girder according to the prior art, and effectively improves the resistance performance against shear force.

In the case of the tapered girder according to the prior art, the maximum shear stress of the transition section 30 is 132 MPa (Fig. 4), whereas in the case of the tapered girder according to the present invention, the rear portion of the transition section 100 Since the maximum shear stress is 96 MPa, the effect of the upper abdominal connecting plate 160 can be confirmed (FIG. 6).

When the slit 141 is formed in the deep part of the front closing plate 140, the front end of the abdominal connecting plate 160 is located in the upper region and the lower region of the slit 141 in the rear surface of the front closing plate 140. It is preferable to combine, and even in this case, the above-mentioned effect can be obtained stably.

On the other hand, the reason why excessively large shear stress occurs at the rear of the transition section 30 in the conventional tapered section girder is the side connecting plate 33 formed at the rear of the transition section 30 and the rear Since the coupling structure of the closing plate 35 takes an angular bending structure, changing this structure can be a fundamental solution.

Therefore, in the case of the tapered girder according to the present invention, a curved structure is adopted so that a pair of rear finishing plates 150 protrude outward. (FIG. 7)

That is, the rear end of the pair of side connecting plates 130 is formed to be biased in front (spaced apart from the front) than the front end of the web plate 23 of the plate girder part 20, and the front of the web plate 23 A pair of rear closing plates 150 having the above-described curved structure are installed between the rear end and the rear end of the pair of side connecting plates 130.

Since this facilitates the shear flow (shear force per unit length), the maximum shear stress is reduced compared to the conventional angled bending structure.

When the transition section takes an angled bending structure, the maximum shear stress of the prior art is 132 MPa (FIG. 4), and the first embodiment of the structure of the transition section of the present invention (when the abdominal connecting plate 160 is added) The maximum shear stress is 96 MPa (FIG. 6).

In contrast, since the maximum shear stress of the second embodiment of the structure of the transition section of the present invention (when the curved rear closing plate 150 is installed) is 64 MPa, the curved structure of the rear closing plate 150 The effect can be confirmed. (FIG. 8)

Hereinafter, structural analysis results for selecting the optimal ratio of the length (L2) of the transition section 100 to the length (Total L) of the shear stress generating section will be described. (FIGS. 9 to 24)

Here, the length of the shear stress generation section (Total L) is defined as the length between the maximum bending moment occurrence point of the box girder part 10 and the maximum bending moment occurrence point of the plate girder part 20. (See Fig. 2)

The length of the shear stress generating section (Total L) is half the length of the box girder part 10 (L1), the length of the transition section 100 (L2), and half the length of the plate girder part 20 (L3) is the sum of

Table 1 shows Examples 1 to 4 regarding the length (L2) of the transition section of the present invention, the length (Total L) of the shear stress generating section and half (L1) of the length of the box girder section 10 are the same And the length of the transition section (L2) (2.5m ~ 5.5m) and half of the length of the plate girder (20) (L3) (13m ~ 10m) are changed. (FIGS. 9 to 12)

The width d1 of the box girder part 10 is 2.5 m, and the width d2 of the plate girder part 20 is set to 1.2 m.

In the case of Example 1, the maximum shear stress is 64 MPa (FIG. 13), in the case of Example 2, the maximum shear stress is 45 MPa (FIG. 14), in the case of Example 3, the maximum shear stress is 37 MPa, (FIG. 15) In the case of 4, the maximum shear stress was found to be 35 MPa (FIG. 16).

That is, as the length (L2) of the transition section increases, the magnitude of the maximum shear stress generated at the rear of the transition section decreases.

However, the difference in shear stress between Example 1 and Example 2 is 19 MPa, the difference between Example 2 and Example 3 is 8 MPa, and the difference between Example 3 and Example 4 is 2 MPa. It was found that the reduction rate of the maximum shear stress decreased as the length (L2) of the transition section increased.

Tables 2 and 3 show the reduction rates of the shear stress described above with respect to Examples 1 to 4.

That is, as the length L2 of the transition section increases, the magnitude of the maximum shear stress generated at the rear of the transition section decreases. Therefore, it cannot be said to be an efficient structure.

Furthermore, the box girder part 10 and the plate girder part 20 can be used by purchasing existing products, but the transition section part 100 must be manufactured and used separately, so the larger the scale, the more disadvantageous it is in terms of economy.

17 to 20 show Examples 5 to 8 regarding the length (L2) of the transition section of the present invention, and Total L, L1, L2, and L3 are the same as Examples 1 to 4.

However, the width (d1) of the box girder part 10 is 2m, and the width (d2) of the plate girder part 20 is set to 0.95m.

In the case of Example 5, the maximum shear stress is 93 MPa (FIG. 21), in the case of Example 6, the maximum shear stress is 79 MPa (FIG. 22), in the case of Example 7, the maximum shear stress is 71 MPa, (FIG. 23) In the case of 8, the maximum shear stress was found to be 64 MPa (FIG. 24).

That is, even in the case of this embodiment, as the length L2 of the transition section increases, the magnitude of the maximum shear stress generated at the rear of the transition section decreases, but when the length L2 of the transition section becomes too long, the maximum shear stress It was found that the decrease rate of

Therefore, among Examples 1 to 4 and Examples 5 to 8 regarding the length (L2) of the transition section of the present invention, it is determined that the section (Examples 2 and 6) having the largest reduction rate of the maximum shear stress is the appropriate length.

That is, it is determined that the optimal ratio of the length (L2) of the transition section 100 to the length (Total L) of the shear stress generating section is 10 to 15%, which is around Example 2 (12.28%).

Hereinafter, a structure for selecting the optimal ratio of the radius of curvature of the rear closing plate 150 of the transition section 100 to the width of the upper flange 21 (or lower flange 22) of the plate girder portion 20 Analysis results are explained. (Figs. 25 to 34)

The length of the shear stress generating section (Total L), half of the length of the box girder part 10 (L1), the length of the transition section part (L2), half of the length of the plate girder part 20 (L3), the box girder part ( The width (d1) of 10) and the width (d2) of the plate girder part 20 were based on Example 2 regarding the length (L2) of the transition section described above.

Table 5 shows Examples 1 to 5 regarding the radius of curvature (R) of the rear closing plate 150 of the transition section of the present invention, and the radius of curvature (R) (400 mm to 750 mm) of the rear closing plate 150 In addition to changing, it shows the ratio to the width (d2) (1,200mm) of the upper flange 21 of the plate girder part 20.

In the case of Example 1, the maximum shear stress is 51 MPa (FIG. 30), in the case of Example 2, the maximum shear stress is 31 MPa (FIG. 31), in the case of Example 3, the maximum shear stress is 31 MPa, (FIG. 32) Example In the case of 4, the maximum shear stress was 39 MPa (FIG. 33), and in the case of Example 5, the maximum shear stress was found to be 41 MPa (FIG. 34).

That is, it was found that the maximum shear stress had the minimum value in Examples 2 and 3.

Therefore, the ratio of the radius of curvature of the rear closing plate 150 to the width of the upper flange 21 is preferably 40 to 48%.

Hereinafter, an embodiment in which an upper abdominal reinforcing plate 170 and a lower abdominal reinforcing plate 180 are added to the front of the front closing plate 140 will be described. (FIGS. 35 and 36)

The upper abdominal reinforcing plate 170 has an upper edge coupled to the lower surface of the upper connecting plate 110 so as to be located on the same plane as the abdominal plate 23 and the abdominal connecting plate 160, and the rear edge is the front closing plate 140. ) It is formed as a standing structure coupled to the upper region of the opening 141 of the front surface of the.

An upward concave portion 171 curved concavely toward the rear upper side is formed in a region between the front upper end and the rear lower end of the upper abdominal reinforcing plate 170 .

The lower abdominal reinforcing plate 180 has a lower edge coupled to the upper surface of the lower connecting plate 120 so as to be located on the same plane as the abdominal plate 23 and the abdominal connecting plate 160, and the rear edge has a front closing plate 140. ) It is formed as a standing structure coupled to the lower region of the opening portion 141 of the front surface of the.

In the region between the front lower end and the rear upper end of the lower abdominal reinforcing plate 180, a downward concave portion 181 curved concavely toward the rear lower side is formed.

Since this structure efficiently transfers the shear force acting on the web connecting plate 160 of the transition section 100 to the box girder section 10, the maximum shear stress generated at the front of the transition section 100 size can be reduced.

36 and 37 show structural analysis results of the transition section 100 having basically the same structure, and FIG. 37 shows the above-described upper abdominal reinforcing plate 170 and lower abdominal reinforcing plate 180 compared to FIG. This added embodiment is shown.

As shown, in the case of the embodiment in which the upper abdominal reinforcing plate 170 and the lower abdominal reinforcing plate 180 are added, it can be seen that the shear stress of the region is reduced from 47 MPa to 35 MPa.

38 shows an embodiment of a bridge to which a tapered girder according to the present invention is applied.

A side girder composed of a box girder part 10, a transition section part 100, and a plate girder part 20 of an I-shaped cross section is installed on the upper part of the pier 30, and the upper plate 40 is installed thereon.

A box girder part 10 with a large section modulus is located at the point where a large bending moment occurs (upper part of the coping 31 of the pier 30), and a plate girder part 20 is located at the center where a relatively small moment occurs. Located.

Since the above has only been described with respect to some of the preferred embodiments that can be implemented by the present invention, as noted, the scope of the present invention should not be construed as being limited to the above embodiments, and the scope of the present invention described above It will be said that the technical idea and the technical idea together with the root are all included in the scope of the present invention.

10: box girder part 11: top plate
12: lower plate 13: side plate
20: plate girder part 21: upper flange
22: lower flange 23: abdominal plate
100: transition section 110: upper connecting plate
120: lower connecting plate 130: side connecting plate
140: Front closing plate 141: Slit
150: rear closing plate 160: abdominal connecting plate
170: upper abdominal reinforcement plate 171: upward concave portion
180: lower abdominal reinforcement plate 181: downward recess

Claims (7)

delete delete A box girder part 10 with a square cross section installed at the front, a plate girder part 20 with an I-shaped cross section installed at the rear, and a transition section installed between the box girder part 10 and the plate girder part 20 contains (100);
The box girder part 10 includes an upper plate 11, a lower plate 12, and a pair of side plates 13,
The plate girder part 20,
an upper flange 21 narrower than the upper plate 11;
a lower flange 22 narrower than the lower plate 12;
Including; the pair of side plates 13 and the same height as the abdominal plate 23,
The transition section 100,
An upper connection plate 110 having a width at the front end equal to that of the upper plate 11, a width at the rear end equal to that of the upper flange 21, and gradually narrowing from the front to the rear;
A lower connection plate 120 having a width at the front end equal to that of the lower plate 12, a width at the rear end equal to that of the lower flange 22, and gradually narrowing from the front to the rear;
One installed between the upper connecting plate 110 and the lower connecting plate 120 so that the height is the same as that of the pair of side plates 13 and the abdominal plate 23 and the gap gradually narrows from the front to the rear. a pair of side connecting plates 130;
a front closing plate 140 installed between the front ends of the pair of side connecting plates 130;
A pair of rear closing plates 150 installed between the rear end of the pair of side connection plates 130 and the front end of the abdominal plate 23;
The front end is coupled to the front closing plate 140 so that it has the same height as the abdominal plate 23 and is positioned on the same plane as the abdominal plate 23, and the rear end is attached to the front end of the abdominal plate 23. In addition to being combined, an abdominal connection plate 160 installed between the upper connection plate 110 and the lower connection plate 120;
The upper edge is coupled to the lower surface of the upper connecting plate 110 so as to be located on the same plane as the abdominal plate 23 and the abdominal connecting plate 160, and the rear edge is the center of the front surface of the front closing plate 140. An upper abdominal reinforcing plate 170 of an upright structure coupled to the upper region of the pregnant part 141;
The lower edge is coupled to the upper surface of the lower connecting plate 120 so as to be located on the same plane as the abdominal plate 23 and the abdominal connecting plate 160, and the rear edge is the center of the front surface of the front closing plate 140. Including; a lower abdominal reinforcing plate 180 of an upright structure coupled to the lower region of the arm 141,
A cutout 141 is formed in the core of the front closing plate 140,
The front end of the abdominal connecting plate 160 is coupled to the upper and lower regions of the cutout 141 of the front surface of the front closing plate 140. According to claim 3,
In the region between the front upper end and the rear lower end of the upper abdominal reinforcing plate 170, an upward concave portion 171 curved concavely toward the rear upper side is formed,
In the region between the front lower end and the rear upper end of the lower web reinforcement plate 180, a downward concave portion 181 curved concavely toward the rear lower side is formed. delete A box girder part 10 with a square cross section installed at the front, a plate girder part 20 with an I-shaped cross section installed at the rear, and a transition section installed between the box girder part 10 and the plate girder part 20 contains (100);
The box girder part 10 includes an upper plate 11, a lower plate 12, and a pair of side plates 13,
The plate girder part 20,
an upper flange 21 narrower than the upper plate 11;
a lower flange 22 narrower than the lower plate 12;
Including; the pair of side plates 13 and the same height as the abdominal plate 23,
The transition section 100,
An upper connection plate 110 having a width at the front end equal to that of the upper plate 11, a width at the rear end equal to that of the upper flange 21, and gradually narrowing from the front to the rear;
A lower connection plate 120 having a width at the front end equal to that of the lower plate 12, a width at the rear end equal to that of the lower flange 22, and gradually narrowing from the front to the rear;
One installed between the upper connecting plate 110 and the lower connecting plate 120 so that the height is the same as that of the pair of side plates 13 and the abdominal plate 23 and the gap gradually narrows from the front to the rear. a pair of side connecting plates 130;
a front closing plate 140 installed between the front ends of the pair of side connecting plates 130;
A pair of rear closing plates 150 installed between the rear end of the pair of side connection plates 130 and the front end of the abdominal plate 23;
The front end is coupled to the front closing plate 140 so that it has the same height as the abdominal plate 23 and is positioned on the same plane as the abdominal plate 23, and the rear end is attached to the front end of the abdominal plate 23. In addition to coupling, an abdominal connection plate 160 installed between the upper connection plate 110 and the lower connection plate 120; includes,
The pair of rear closing plates 150 are formed curved so as to protrude outward,
When the length between the maximum bending moment occurrence point of the box girder part 10 and the maximum bending moment occurrence point of the plate girder part 20 is the length of the shear stress generating section,
The tapered girder, characterized in that the length of the transition section 100 is 10 to 15% of the length of the shear stress generating section. According to claim 6,
The tapered girder, characterized in that the ratio of the radius of curvature of the rear closing plate 150 to the width of the upper flange 21 is 40 to 48%.

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