JP2002348813A - Method for constructing main tower of diagonal tensioning bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for constructing a main tower of a diagonal tensioning bridge, which reduces the weight of a steel shell portion of the main tower, prevents stress to concentrate on a lower bed portion of the steel shell portion in a concrete portion, and improves the workability when the main tower is constructed. SOLUTION: According to the method, a plurality of steel shell units 24 are stacked on a main tower construction portion of the diagonal tensioning bridge to set the steel shell portion 20, and then concrete is lined along the steel shell portion 20 such that a bridge-axially central portion thereof is left like a belt, to thereby form a pre-cast concrete portion 22A. Thereafter, a diagonal member 14 is anchored to each anchoring structure 18 of the steel shell portion 20 via an anchor 16, and tension T is introduced to each diagonal member 14. Lastly, concrete is placed on the bridge-axially central portion of the steel shell portion 20. In this manner, the pre-cast concrete portion 22A is not formed at the bridge-axially central portion of the steel shell portion 20, and therefore a horizontal component (tensile force) of a diagonal tensile force T is borne only by the steel shell portion 20, while a vertical component (compressive force) of the diagonal tensile force T is borne by a composite cross section between the steel shell portion 20 and the pre-cast concrete portion 22A. As a result, the burden on the steel shell portion 20 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a main tower of a cable-stayed bridge, and more particularly to a method of constructing a main tower side diagonal material fixing section.

[0002]

2. Description of the Related Art Generally, a cable-stayed bridge has a structure in which a plurality of pairs of diagonal members are stretched over a plurality of upper and lower stages on both sides in the bridge axis direction of a main tower. Concrete is wound around a steel shell having a plurality of pairs of fixing structures for fixing a plurality of pairs of diagonal members.

However, in a conventional cable-stayed bridge, in order to prevent a tensile load from acting on the concrete part, the introduction of the diagonal material tension when constructing the main tower is performed in a state before the concrete is rolled around the steel shell part. It is supposed to do.

[0004]

However, in the case where the introduction of the diagonal material tension is performed before the concrete is rolled up as described above, it is necessary to cover all of the diagonal material tension with the steel shell. In order to secure the strength, the weight of the steel shell is inevitably increased, which causes a problem that the cost of the cross-linking equipment increases.

[0005] Further, since all of the diagonal material tension is taken up by the steel shell, there is also a problem that stress concentration tends to occur at the lower end of the steel shell in the concrete part.

Further, since the weight of the steel shell becomes large, there is also a problem that it is difficult to perform the construction in a place where the construction and transportation have a weight limit.

[0007] The present invention has been made in view of the above-mentioned circumstances, and reduces the weight of the steel shell of the main tower and causes stress concentration at the lower end of the steel shell in the concrete part. It is an object of the present invention to provide a method for constructing a main tower of a cable-stayed bridge, which can prevent the occurrence of the problem and improve the workability when constructing the main tower.

[0008]

The present invention achieves the above object by introducing diagonal tension in a state where concrete is wound up to a certain extent on a steel shell. is there.

That is, the method for constructing a main tower of a cable-stayed bridge according to the present invention is a method for constructing a main tower of a cable-stayed bridge in which a plurality of pairs of diagonal members are stretched over a plurality of upper and lower stages on both sides in the bridge axis direction of the main tower. After installing a steel shell portion having a plurality of pairs of anchoring structures for anchoring the plurality of pairs of diagonal members on the main tower building portion of the cable stayed bridge, The concrete is rolled up so as to leave the central part of the steel shell in the bridge axis direction, and then tension is introduced into the respective diagonal members fixed to the respective anchoring structures. It is characterized by placing concrete in the central part.

The type of the cable-stayed bridge is not particularly limited as long as a plurality of pairs of diagonal members are stretched over a plurality of upper and lower stages on both sides of the main tower in the bridge axis direction. Or a cable-stayed bridge, such as an extra-dosed bridge with a relatively low main tower height, in which the main tower side diagonal material anchoring section is concentrated at the top of the main tower. Good.

The specific configuration of the "steel shell" is not particularly limited as long as it has a plurality of pairs of fixing structures for fixing a plurality of pairs of diagonal members.

[0012]

As described above, the method for constructing a main tower of a cable-stayed bridge according to the present invention comprises a plurality of pairs of fixing members for fixing a plurality of pairs of diagonal members to a main tower constructing portion of the cable-stayed bridge. After installing the steel shell having the anchoring structure, concrete is wrapped around the steel shell so as to leave the central part in the bridge axis direction, and then tension is applied to each diagonal material anchored to each anchoring structure. After the introduction, finally, concrete is poured into the central portion of the steel shell in the bridge axis direction, so that the following operation and effect can be obtained.

That is, by introducing the diagonal material tension after rolling up the concrete so as to leave the central part in the bridge axis direction with respect to the steel shell portion, the horizontal component (tensile force) of the diagonal material tension is obtained. The vertical component (compression force) of the diagonal material tension can be handled by the composite section of the steel shell and the concrete while the steel shell only takes charge.

Therefore, the load on the steel shell can be reduced as compared with the conventional structure in which all the diagonal material tension is received by the steel shell, and the weight of the steel shell can be reduced accordingly. it can. Moreover, at that time, it is possible to prevent the tensile load from acting on the concrete portion.

In addition, since the vertical component of the diagonal material tension acting as a compressive force is taken over by the composite cross section of the steel shell and the concrete, stress concentration occurs in the concrete portion located at the lower end of the steel shell. Can be prevented beforehand.

Furthermore, since the weight of the steel shell can be reduced, the cost of the cross-linking equipment can be reduced.
In addition, it is easy to perform construction in places where there is a limit on the weight of erection and transportation.

As described above, by adopting the method for constructing the main tower of the cable-stayed bridge according to the present invention, it is possible to reduce the weight of the steel shell of the main tower, and at the lower end of the steel shell in the concrete part. The occurrence of stress concentration can be prevented, and the workability at the time of building the main tower can be improved.

As described above, the specific configuration of the "steel shell" is not particularly limited. However, the installation of the steel shell is performed by a plurality of steel shell units divided for each pair of fixing structures. If the construction is carried out by stacking, construction and transportation can be performed in units of steel shell units whose weight is sufficiently small, so construction in places where the construction and transportation are limited by weight is extremely easy. be able to.

[0019] In this case, if the stacking of the steel shell units is performed through the laminating plane set as the cleave cut plane in both the bridge axis direction and the bridge axis orthogonal direction, the stacking at the time of stacking is performed. Construction errors can be minimized, which can further improve the workability.

At this time, if the surface accuracy of the lamination surface is increased in advance by surface processing in a factory or the like, it is possible to stack the steel shell units by metal touch (high-precision surface contact state). Therefore, welding work on site can be dispensed with, thereby greatly improving workability.

If each steel shell unit is provided with a plurality of stud dowels on its outer peripheral surface, the vertical component of the diagonal material tension acting as a compressive force on the steel shell can be reduced by each steel shell unit. Since the power can be efficiently transmitted to the concrete portion via the stud dowel of the shell unit, the compressive force can be more effectively applied to the composite cross section of the steel shell portion and the concrete portion.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a main part of a cable-stayed bridge 10 to be subjected to a method for constructing a main tower according to an embodiment of the present invention, as viewed from a direction orthogonal to the bridge axis, and FIG. FIG. 2 is a view taken along line II-II. FIG. 3 is a detailed view of a part III in FIG. 1, and FIG. 4 is a detailed view of a cross section taken along line IV-IV of FIG.

As shown in these figures, this cable stayed bridge 10
Is an extradosed bridge having a relatively low height of the main tower (about 16 m), in which ten pairs of diagonal members 14 are stretched on both sides in the bridge axis direction of the main tower 12 in ten vertical steps. . Each of these diagonal members 14 is composed of a main tower side diagonal material fixing section 12 </ b> A arranged above the main tower 12 and a main tower 12
And a main girder-side diagonal material fixing portion (not shown) arranged on both sides in the bridge axis direction. At this time, each of the diagonal members 14 is stretched with a larger inclination angle as the lower one is located.

The main tower side diagonal material fixing section 12A is composed of a steel shell portion 20 having ten pairs of fixing structures 18 for fixing each of the ten pairs of diagonal members 14 through a fixing tool 16, The concrete part 22 is wound around the shell part 18.

The steel shell portion 20 is formed by stacking ten steel shell units 24 formed separately for each pair of fixing structures 18 (this will be described later).

On the other hand, the concrete section 22 is composed of a pre-cast concrete section 22A and a post-cast concrete section 22B.

The precast concrete portion 22A is made of steel shell 2
The bridge is formed by rolling up concrete so that the central portion of the bridge axis direction 0 and the central portion of the bridge axis direction are left in a strip shape. In addition, after-cast concrete part 2
2B is formed by pouring concrete into the concave space left in a strip shape on both sides of the central portion of the steel shell 20 in the bridge axis direction. Each of these post-cast concrete sections 22
The surface of B is formed at a position one step lower than the surface of the precast concrete portion 22A.

FIG. 5 is a side view showing the steel shell 20.
FIG. 6 is a side view showing the steel shell unit 24 of the second stage from the top as an example out of the ten steel shell units 24 constituting the steel shell part 20. FIG. 7 is a perspective view showing a step of stacking the steel shell units 24.

As shown in these figures, each of the steel shell units 24 is accommodated in a long rectangular frame 26 extending in the bridge axis direction.
A pair of fixing structures 18 are provided.

The rectangular frame 26 includes a pair of long wall plates 28,
The pair of short wall plates 30 are welded and fixed to both end surfaces of the long wall plates 28 in the bridge axis direction.

Each of the long wall surfaces 28 has an upper end surface 28a and a lower end surface 28b formed as cut-away surfaces. That is, although the central portion of the upper end surface 28a and the lower end surface 28b is formed as a horizontal plane,
Both ends in the bridge axis direction are formed as inclined surfaces inclined obliquely downward.

Each short wall surface plate 30 also has an upper end surface 3.
0a and the lower end surface 30b are both formed as cut-away surfaces. That is, the upper end surface 30a and the lower end surface 30b are formed in a mountain shape, and both ends in the direction orthogonal to the bridge axis are formed as horizontal surfaces by the thickness of each long wall plate 28. At approximately the center of each of these short wall plates 30, a diagonal material insertion hole 30 for inserting the diagonal material 14 is provided.
c is formed.

A number of stud dowels 32 are provided on the outer peripheral surface of the rectangular frame 26. These stud dowels 3
2 is a portion of each long wall plate 28 other than the central portion in the bridge axis direction and a diagonal material insertion hole 30c in each short wall plate 30
Are provided in a predetermined arrangement over the entire area.

In each fixing structure 18, a fixing plate 34 for receiving the fixing tool 16 is fixedly supported by the rectangular frame 26 via three support plates 36, 38, and 40 arranged in a U-shape. I have.

The fixing plate 34 includes a support plate 36
Is welded to the center of the surface near the center of the rectangular frame 26. The support plate 36 is disposed along an inclined plane orthogonal to the inclination angles of the upper end surface 28a and the lower end surface 28b of the long wall plate 28, and both end surfaces are welded to the long wall plates 28 on both sides. I have. Upper and lower pair of plates 3
8, 40 are arranged substantially parallel to the upper end surface 28a and the lower end surface 28b of the long wall plate 28, and the end surface near the center of the rectangular frame 26 is welded to the support plate 36,
Both end surfaces are welded to the long wall plates 28 on both sides. The fixing plate 34 and the support plate 36 include
The fixing tool fixing holes 34a and 36a are formed.

As shown in FIG. 5, the upper end surface 28a and the lower end surface 28 of the long wall plate 28 in each steel shell unit 24 are formed.
The downward inclination angle of both ends in the bridge axis direction of the steel shell unit 2
The angle is set to be the same as the stretching angle of the diagonal member 14 fixed to the sheet 4. For this reason, the steel shell unit 24 located at the lower stage
The lower the inclination angle is, the larger the value is set.

The upper and lower end surfaces 28a, 28b of the long wall plate 28 and the upper and lower end surfaces 30a, 30b of each short wall plate 30 in each of the steel shell units 24 are finished with high precision. The laminated surfaces 20a between the 24 are metal touch (high-precision surface contact state).

The steel shell unit 24 located at the uppermost stage
, The upper end surfaces 28a and 30a of the short wall plates 30 and the long wall plate 28 and the short wall plates 3 of the steel shell unit 24 located at the lowermost stage.
The lower end surfaces 28b and 30b of 0 are formed along a horizontal plane. The base plate 42 is fixed by welding to the lower end surface 28b of the steel shell unit 24 located at the lowermost stage.

Next, the main tower building process (more specifically, the main tower side diagonal material fixing section 12A in the main tower 12) of the present embodiment will be described.

First, each steel shell unit 24 is manufactured in advance at a factory or the like. At this time, the upper and lower end surfaces 28a, 2a, 2b of the long wall plate 28 and the short wall plate 30 of each steel shell unit 24 are formed.
8b and 30a, 30b are subjected to surface processing to sufficiently enhance the surface accuracy.

Next, ten steel shell units 24 are sequentially stacked on the main tower building portion of the cable stayed bridge 10 as shown in FIG. As shown in FIGS. 8 and 9, concrete is rolled up so as to leave a central portion in the bridge axis direction and a central portion in the bridge axis orthogonal direction, respectively, to form a precast concrete portion 22A.

After that, the oblique members 14 are fixed to the fixing structures 18 of the respective steel shell units 24 via the fixing tools 16, and a tension T (indicated by an arrow in the drawing) is introduced to each of the oblique members 14.

Finally, concrete is poured into the central portion of the steel shell portion 20 in the bridge axis direction to form a post-cast concrete portion 22B as shown in FIGS.

In the main tower building process, since the precast concrete portion 22A is not formed at the central portion of the steel shell portion 20 in the bridge axis direction, the horizontal component (tensile force) of the diagonal material tension T is only the steel shell portion 20. On the other hand, on the other hand, the diagonal material tension T
The vertical component (compression force) of the steel shell portion 20 and the pre-cast concrete portion 22A is covered by the composite section.

Therefore, the load on the steel shell portion 20 can be reduced as compared with the conventional structure in which the steel shell portion 20 entirely receives the diagonal material tension T. In addition, the weight of the steel shell portion 20 can be reduced by that much, so that the cost of the cross-linking equipment can be reduced. Further, since the weight of the steel shell portion 20 can be reduced in this manner, it is easy to perform construction in a place where there is a weight limit in erection and transportation.

Further, the diagonal material tension T acting as a compressive force
Of the vertical component of the steel shell portion 20 and the pre-cast concrete portion 22
By taking charge of the composite cross section with A, it is possible to prevent stress concentration from occurring at the concrete portion located at the lower end of the steel shell portion 20 beforehand.

In the main tower building process, each steel shell unit 24 undergoes some elongation in the bridge axis direction due to the introduction of the diagonal material tension T. After this elongation, the post-cast concrete portion 22B is formed. So the concrete part 22
Can be prevented from being subjected to a tensile load.

As described above, by adopting the method for constructing the main tower of the cable-stayed bridge according to the present embodiment, the steel shell 20
Can be reduced in weight, stress concentration can be prevented from occurring at the lower end portion of the steel shell portion 20 in the concrete portion 22, and workability at the time of main tower construction can be improved. .

In particular, in the present embodiment, the steel shell portion 20 is installed by stacking a plurality of steel shell units 24 formed separately for each pair of fixing structures 18. Carrying can be carried out in units of the steel shell unit 24 having a sufficiently small weight (a unit of about 5 tf or less), which makes it possible to extremely easily perform construction in places where there is a weight limit in erection and carrying. .

Further, in this embodiment, the stacking of the steel shell units 24 is performed via the laminating surface 20a set as the cut-away surface in both the bridge axis direction and the bridge axis orthogonal direction. Therefore, the construction error at the time of stacking can be minimized, and thereby the workability can be further improved.

Moreover, in the present embodiment, the lamination surface 20
a of upper end surfaces 28a, 30 of each of the steel shell units 24 constituting
a and the lower end surfaces 28b and 30b are sufficiently improved in advance by surface processing in a factory or the like, and the steel shell units 24 are stacked by metal touch. It is possible to eliminate the necessity of welding work between the 24 pieces, thereby greatly improving workability.

In this embodiment, each of the steel shell units 24 has a plurality of stud dowels 32 on its outer peripheral surface.
The vertical component of the diagonal material tension T acting as a compressive force on the steel shell portion 20 is applied to the precast concrete portion 22A via the stud dowel 32 of each steel shell unit 24. Can be efficiently transmitted to the steel shell 20 and the precast concrete 22A.
And the compression force load on the combined cross section can be more effectively performed.

[Brief description of the drawings]

FIG. 1 is a side view showing a main part of a cable-stayed bridge to be subjected to a method for constructing a main tower according to an embodiment of the present invention, as viewed from a direction orthogonal to a bridge axis.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a detailed view of a part III in FIG. 1;

FIG. 4 is a detailed sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a side view showing a steel shell of a main tower in the cable stayed bridge.

FIG. 6 is a side view showing, as an example, a steel shell unit in the second stage from the top of the ten steel shell units constituting the steel shell part.

FIG. 7 is a perspective view showing a step of stacking the above-mentioned steel shell units.

FIG. 8 is a view similar to FIG. 3, showing a state of introduction of diagonal material tension in the main tower building method.

FIG. 9 is a view similar to FIG. 4, showing how the diagonal member tension is introduced;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cable stayed bridge (extra-dosed bridge) 12 Main tower 12A Main tower side diagonal material anchoring part 14 Diagonal material 16 Anchor 18 Anchor structure 20 Steel shell part 20a Stacking surface 22 Concrete part 22A Precast concrete part 22B Post-cast concrete part 24 Steel shell unit 26 Rectangular frame 28 Long wall plate 30 Short wall plate 28a, 30a Upper end surface 28b, 30b Lower end surface 30c Diagonal material insertion hole 32 Stud dowel 34 Fixing plate 34a, 36a Fixing device fixing hole 36, 38, 40 Support plate 42 Base plate 50 Main girder T Diagonal material tension

Continuing from the front page (72) Inventor Akio Kasuga 13-4 Arakicho, Shinjuku-ku, Tokyo Sumitomo Construction Co., Ltd. (72) Inventor Katsuhiko Mizuno 13-13 Arakicho, Shinjuku-ku, Tokyo Sumitomo Construction Co., Ltd. (72 ) Inventor Masaharu Kuwano 13-4 Arakicho, Shinjuku-ku, Tokyo Sumitomo Construction F-term (reference) 2D059 AA27 AA41 BB08 CC25 DD28 GG55 GG61

Claims (4)

[Claims] 1. A method for constructing a main tower of a cable-stayed bridge, comprising a plurality of pairs of diagonal members stretched over a plurality of upper and lower stages on both sides in the bridge axis direction of the main tower. After installing a steel shell portion having a plurality of pairs of anchoring structures for anchoring the plurality of pairs of diagonal members, the central portion of the steel shell portion in the bridge axis direction is left for the steel shell portion. Laying concrete, thereafter, introducing tension to each of the diagonal members fixed to each of the fixing structures, and finally pouring concrete to a central portion of the steel shell in the bridge axis direction. How to build the main tower of a cable-stayed bridge. 2. The cable-stayed bridge according to claim 2, wherein the installation of the steel shell portion is performed by stacking a plurality of steel shell units formed separately for each pair of the fixing structures. Main tower construction method. 3. The stacking of each of the steel shell units is performed via a lamination surface set as a mountain-cutting surface in both the bridge axis direction and the bridge axis orthogonal direction. The main tower construction method of the cable stayed bridge described. 4. The main tower of a cable-stayed bridge according to claim 2, wherein each of the steel shell units has a plurality of stud dowels provided on an outer peripheral surface of the steel shell unit. How to build.