JP6763010B2 - Cable-stayed bridge and how to build a cable-stayed bridge - Google Patents

Description

The present invention relates to a cable-stayed bridge structure and a method for constructing a cable-stayed bridge having such a structure.

Conventionally, an edge girder type cable-stayed bridge having a main girder concrete portion is known as a cable-stayed bridge in which the main girder is supported by a cable-stayed material fixed to the main tower (see, for example, Patent Document 1). ).

Japanese Unexamined Patent Publication No. 6-81322

However, the cable-stayed bridge having the main girder concrete portion as described above tends to have a large weight, and has a problem that it is not easy to improve the seismic resistance and durability.

In view of the above points, it is an object of the present invention to make it possible to improve the seismic resistance and durability of a cable-stayed bridge relatively easily.

In order to achieve the above object, the present invention
An oblique bridge in which the bridge girder is supported by a cable extending from the main tower.
The main girder provided on both sides of the width of the bridge girder and to which the cable is connected, respectively,
The lower horizontal rib provided between the main girders and
With the upper horizontal rib connected to the upper part of the lower horizontal rib,
With the deck plate connected to the upper part of the upper horizontal rib,
It is characterized by being equipped with.

As a result, it is possible to easily transport the deck plate or the like including the upper horizontal rib while ensuring the rigidity by the lower horizontal rib, and the seismic resistance and durability of the cable-stayed bridge can be improved with a relatively lightweight structure. It can be improved relatively easily.

According to the present invention, the seismic resistance and durability of a cable-stayed bridge can be improved relatively easily.

It is a side view which shows the schematic structure of a cable-stayed bridge. It is a front view which shows the schematic structure of a cable-stayed bridge. It is sectional drawing at the position of a cable fixing part and a horizontal rib in a central span part. It is a cross-sectional view which shows the joint part of the lower horizontal rib and the vertical girder at the position of the cable fixing part and the horizontal rib in the central span part. It is a top view in a state where the deck plate and the upper horizontal rib which show the joint part of the lower horizontal rib and the vertical girder at the position of the cable fixing part and the horizontal rib in the central span part are removed. It is sectional drawing at the position of the lateral rib other than the cable fixing part in the central span part. It is a cross-sectional view at the position between the lateral ribs in the central span portion. It is sectional drawing at the position of a cable fixing part and a horizontal rib in a side span part. It is a cross-sectional view at the position of the lateral rib other than the cable fixing part in the side span part. It is a cross-sectional view at the position between the lateral ribs in a side span portion. It is a cross-sectional view at the position of the main tower. It is explanatory drawing which shows typically the example of the process of the main part in the erection process.

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

(Outline overall structure of cable-stayed bridge)
In the cable-stayed bridge, as shown in FIGS. 1 and 2, one end of the cable 2 is fixed to the upper part of the main tower 1 and the other ends of the cables 2 arranged radially are the main girders on both sides of the width of the bridge girder 50. It has a structure that is fixed to the outside and supports the main girder. The fulcrums that support the main girder from the land side are arranged on the abutment 3, the intermediate pier 4, and the main tower 1. The intermediate pier 4 is arranged to reduce the deflection due to the live load on the central span 5 side, and can be omitted depending on the structural conditions. As in the present embodiment, when the length of the central span 5 is relatively longer than that of the side span 6, the upward reaction force generated in the abutment 3 and the intermediate pier 4 becomes large, the side. As will be described later with reference to FIGS. 8 to 10, the lower concrete slab 26 as a counterweight can be arranged over the entire length of the span 6 to reduce or suppress the influence of the upward reaction force. ..

(Structure of bridge girder 50 with 5 central spans)
The bridge girder 50 in the central span 5 portion has a structure different from each other depending on the presence or absence of fixing of the cable 2 according to the position in the bridge axis direction and the presence or absence of the lateral rib.

(Position where cable 2 is fixed in the central span 5 part)
At the position where the cable 2 is fixed, as shown in FIG. 3, between the main girders 10 on both sides having the main girder web on which the main girder lower flange 11 and the main girder upper flange are formed, in the bridge axis direction. A deck plate 7 to which the trafrib type vertical rib 8 (U rib) and / or the flat rib type vertical rib 9 is attached to the lower surface side is provided, and the lower horizontal rib 16 and the upper horizontal rib 19 in the direction perpendicular to the bridge axis are provided. It is provided. The lower lateral rib 16 is composed of, for example, an upper flange 16a, a lower flange 16b, and a single I-shaped cross-sectional member having an inspection path hole 16d, and is erected between the main girders 10 on both sides via a splicing plate 17. Has been done. Further, the upper horizontal rib 19 is composed of an I-shaped cross-sectional member having an upper flange 19a and a lower flange 19b, and is erected between the main girders 10 on both sides via a splicing plate 21. The lower lateral rib 16 and the upper lateral rib 19 are connected and integrated by joining the upper flange 16a of the lower lateral rib 16 and the lower flange 19b of the upper lateral rib 19 by, for example, high-strength bolts. ..

As shown in FIG. 4, the upper horizontal rib 19 is integrally attached to the lower surface side of the deck plate 7 so that the trafrib type vertical rib 8 is fitted into the recess 19c formed in the upper portion. The deck plate 7, the trough rib type vertical rib 8, and the upper horizontal rib 19 integrally formed as described above are divided into, for example, a length of about 14 m or less in the bridge axis direction and a width of about 3 m or less. By being separated from the lower horizontal rib 16 and being kept low in height, it is possible to facilitate transportation from the manufacturing factory to the site by truck or the like.

As shown in FIG. 5, a vertical girder 13 connecting the lower horizontal ribs 16 in the front-rear direction in the bridge axis direction is arranged at one location in the central portion of the lower horizontal rib 16 so as to be separated from the upper horizontal rib 19 and the like. The grid girder structure with the lower horizontal ribs and the vertical girder 13 ensures the rigidity at the time of erection and reduces the cross-sectional force due to the truck load due to the load distribution action. Here, FIG. 5 is drawn without the deck plate 7 and the upper horizontal rib 19 for convenience. The vertical girder 13 and the lower horizontal rib 16 are not limited, but are preferably bolted in consideration of fatigue durability. That is, the vertical girder 13 and the lower horizontal rib 16 have a lattice girder structure formed by combining them, and have a structure that can withstand the weight of the steel deck member and the lower concrete deck slab to be installed later. Becomes easier. Here, since a large fatigue stress is likely to act on the lower lateral rib 16, it is preferable to adopt a coupling structure using bolts having excellent fatigue resistance. Therefore, for example, the heights of the upper flange upper surface and the lower flange lower surface of the lower horizontal rib 16 and the vertical girder 13 are matched, and the three members of the lower horizontal rib 16 and the vertical girders 13 on both sides are attached to the upper and lower splicing plates 32. While joining with (splice plate), the web of the lower horizontal rib 16 and the flange portion of the CT shaped steel 18 and the web of the vertical girder 13 and the web portion of the CT shaped steel 18 are bolted together using the CT shaped steel 18. As a result, the lower horizontal rib 16 and the vertical girder 13 can be connected only with bolts. In order to avoid interference between the upper horizontal ribs 16 and the upper side splicing plate 32 of the vertical girders 13 and the upper horizontal ribs 19, a recess 33 may be formed in the lower part of the upper horizontal ribs 19.

Further, the upper horizontal rib 19 is preferably a member long in the bridge axis direction because the connection at the site becomes complicated when the number of the trafrib type vertical ribs 8 and the like is large, and as described above, the bridge shaft It is divided at short intervals of about 3 m or less in the perpendicular direction, and is connected by the splicing plate 20 in the direction perpendicular to the bridge axis. At this time, joining the steel slabs to each other at the site may be a relatively difficult technique due to the long extension of the joint and the low rigidity of the steel slabs themselves, but the lattice having sufficient rigidity Temporarily place the upper flange 16a of the lower horizontal rib 16 and the lower flange 19b of the upper horizontal rib 19 on the girder structure, and after sufficient adjustment of the joint, weld and bolt the steel deck slabs. By being able to do this, it is possible to easily simplify the erection work.

(Position where the upper horizontal rib 19 is arranged other than the fixing portion of the cable 2 in the central span 5 portion)
At the position where the cable 2 is not fixed in the bridge axis direction, that is, at the position between the positions where the cable 2 is fixed and where the upper horizontal rib 19 is provided, for example, at a position having an interval of 3 to 4 m, the above A lower horizontal rib 16 composed of such an I-shaped cross-sectional member may be used, but instead, as shown in FIG. 6, a diagonal member 23 made of shaped steel and an upper and lower chord member 24 are joined. A truss structure may be used. As a result, the steel weight can be reduced and the economic efficiency can be improved, and a space through which the inspection path for bridge inspection passes can be easily secured.

(Position where the upper horizontal rib 19 is not arranged in the central span 5 part)
The portion of the bridge girder 50 between the position where the upper horizontal rib 19 and the lower horizontal rib 16 and the diagonal member 23 and the upper and lower chord members 24 are provided as described above is not necessarily required, but is shown in FIG. 7, for example. As described above, for example, a partial lower surface shielding plate 14 made of FRP and a handrail 15 for an inspection passage, which functions as a floor of the inspection path, are provided so that the bridge inspection work can be facilitated.

(About ensuring wind resistance stability)
In order to improve the wind resistance stability, the fairing 12 may be provided on the outer side of the main girder 10, as shown in FIGS. 3, 6, 7, and the like. Further, the vertical girder 13 as described above may act as a baffle plate, or the partial lower surface shielding plate 14 may be at least a predetermined distance (for example, 3.5 m or the entire surface) from the lower part of the main girder 10 toward the center in the width direction of the bridge girder. ) May be provided so as to act as a windshield plate.

(Structure of bridge girder 50 with 6 side spans)
As shown in FIGS. 8 to 10, the bridge girder 50 in the side span 6 portion depends on the presence / absence of fixing of the cable 2 according to the position in the bridge axial direction and the presence / absence of the lateral rib as in the central span 5 portion. Although they have different structures from each other, the structure of each steel member is the same as that of the central span 5 portion. However, the lower concrete slab 26 is arranged on the upper portion of the main girder lower flange 11 and the like, and the cost can be reduced by shortening the side span 6 portion and shortening the entire bridge length. That is, the lower concrete slab 26 acts as a counterweight for canceling the negative reaction force generated in the abutment 3 and the intermediate pier 4 by shortening the side span 6, and is synthesized by synthesizing with the steel member. It can act as a lower flange member of the box girder structure (pseudo box girder structure). It should be noted that such a lower concrete floor slab 26 can be easily omitted except in the vicinity of the fulcrum portion when it is not necessary to shorten the side span 6.

(Structure near main tower 1)
In one part of the main tower, for example, it is necessary to provide a bearing for transmitting the inertial force of the superstructure during an earthquake to the substructure. This bearing must have a certain degree of flexibility in the direction of the bridge axis in order to release thermal stress, and in the direction perpendicular to the bridge axis, it is relative so that the main girder 10 and the main tower 1 do not collide with each other. It is necessary to surely prevent the target movement. Further, the horizontal force acting on this bearing supports most of the inertial force acting on the mass of the entire main girder 10, and therefore tends to be on a very large scale. Therefore, for example, a lower concrete floor slab 26 having a predetermined width is arranged on the main girder 10 near the fulcrum to improve the rigidity in the horizontal direction, alleviate the stress concentration generated near the fulcrum, and the lower concrete. The superstructure side concrete protrusion 27 is provided on the lower side of the floor slab 26, while the substructure side concrete protrusion 28 is provided on the substructure side, and a rubber bearing 31 or the like is vertically placed between them. Relative movement of the main girder 10 and the substructure in the direction perpendicular to the bridge axis can be reliably prevented. Since a large out-of-plane bending moment acts on the lower concrete floor slab 26 near the fulcrum, a full web horizontal rib 29 similar to the upper horizontal rib 19 shown in FIG. 3 is arranged, and the horizontal rib 29 and the horizontal rib 29 are arranged. A fulcrum concrete cross beam 30 having a composite structure may be arranged.

(How to build a cable-stayed bridge)
The cable-stayed bridge as described above can be erected by a traveler crane, for example, by the steps shown in FIG. 12 and the following.

Step1: The main girder 10 (main girder block) is erected in an overhanging state (FIG. 12 (a)).

Step2: A lower horizontal rib 16 (lower horizontal rib block) having an I cross section is erected between the main girders 10 (FIG. 12 (b)). As a result, the distance between the fixed points against the lateral buckling of the main girder 10 can be shortened, so that the proof stress of the main girder 10 in the overhanging state can be improved.

Step3: A vertical girder 13 (vertical girder block) is erected between the lower horizontal rib blocks (FIG. 12 (c)). As a result, the distance between the fixed points of the lower lateral rib 16 against lateral tilt buckling can be shortened, so that the strength of the lower lateral rib 16 can be improved.

Step 4: A steel plate block including deck plates 7 on both sides, a trough rib type vertical rib 8 and a flat rib type vertical rib 9 is erected as a scaffold for cable erection (FIG. 12 (d)). Here, if the overhanging strength of the main girder 10 is insufficient, a lightweight scaffolding may be separately arranged.

Step 5: Cable 2 is erected (FIG. 12 (e)). As a result, the vicinity of the tip of the overhanging portion is fixed by the cable 2, and the proof stress of the main girder 10 can be improved.

Step6: The remaining steel plate block is erected, the joint of the steel plate block is adjusted, and then the whole is joined to complete the main girder 10 between the cables 2 (FIG. 12 (f)).

Here, the above-mentioned erection of a traveler crane has merits such as being less affected by the usage conditions under the girder and the equipment used being small and economically superior, but the capacity of the traveler crane is limited. The weight of the member that can be erected from the crane is relatively small, and it is generally difficult to apply it to heavy members such as box girders. On the other hand, in the main girder structure as in the present embodiment, a lightweight I-section member is used as a basis, and even if the I-section member has relatively low rigidity according to the progress of the erection step, these are combined. As a result, the members are sequentially stiffened so that a lattice girder structure having sufficient rigidity is formed before the heaviest steel deck member is erected, which facilitates the erection of an economical traveler crane. Will be possible.

As described above, by applying the edge girder type, by having the main girder of the I cross section on both sides of the width, it is possible to significantly reduce the steel weight as compared with the box girder structure.

Further, when the main girder in which the steel plate and the edge girder type main girder are integrated is divided into a shape capable of transporting the members, each member has a rigidity that allows transportation and on-site assembly. And can be easily made to have a structure, and can be easily assembled in the field when the steel plate and the main girder of the model are integrated.

In addition, by connecting adjacent horizontal ribs with vertical girders to distribute the load and reduce the cross-sectional force, the cross-section of the horizontal ribs can be reduced in addition to avoiding a decrease in the fatigue resistance of the horizontal ribs themselves due to the installation of the vertical girders. It can be easily made possible to improve the economic efficiency.

In addition, the lower concrete floor slab as described above has a pseudo-box girder structure for improving the rigidity of the main girder, a structure for transmitting inertial force during an earthquake from the main girder to the substructure, and a negative reaction force at the end fulcrum. It can be used as a counterweight structure that resists resistance, and can contribute to expanding the applicable range of the main girder in which the steel deck and edge girder type main girder are integrated and overcoming structural weaknesses. ..

In addition, by applying the truss structure to the lower horizontal rib structure using shaped steel as a diagonal member, the weight of the horizontal rib steels arranged in large numbers at intervals of, for example, about 3 to 4 m can be reduced, and inspections for maintenance can be performed. It is easy to secure a space for the road to pass through.

In addition, partial underside shielding plates using FRP panels arranged at the same level as the lower flanges of the main girder on both sides of the width are used as countermeasures for improving wind resistance stability and as the floor of the inspection road for maintenance. It is a structure that also has the function of, and can reasonably improve the wind resistance stability, which is a weak point of the edge girder model.

1 Main tower
2 cable
3 Hashidai
4 Intermediate pier
5 Central span
6 side span
7 deck plate
8 Traf rib model Vertical rib
9 Flat rib type Vertical rib
10 main girder
11 Main girder lower flange
12 fairing
13 vertical girder
14 Partial bottom shield
15 Handrails for inspection passages
16 Lower horizontal rib
16a Upper flange
16b lower flange
16d inspection path hole
17 Splicing board
18 CT section steel
19 Upper horizontal rib
19a Upper flange
19b Lower flange
19c recess
20 splicing board
21 Splicing board
23 Diagonal material
24 Upper and lower string members
26 Lower concrete plate
27 Superstructure side concrete protrusion
28 Substructure side concrete protrusion
29 Horizontal rib
30 fulcrum concrete cross beam
31 Rubber bearings
32 splicing board
33 recess
50 bridge girder

Claims (7)

A cable-stayed bridge in which the bridge girder is supported by a cable extending from the main tower.
The main girder provided on both sides of the width of the bridge girder and to which the cable is connected, respectively,
The lower horizontal rib provided between the main girders and
With the upper horizontal rib connected to the upper part of the lower horizontal rib,
With the deck plate connected to the upper part of the upper horizontal rib,
With
The cable-stayed bridge is characterized in that the lower horizontal rib is configured to ensure the rigidity of the deck plate at least in the central portion in the width direction . The cable-stayed bridge according to claim 1.
The cable-stayed bridge is characterized in that the upper horizontal rib and the deck plate are formed by connecting the partial horizontal ribs and the partial deck plates that are divided into a plurality of parts in the width direction of the bridge girder. A cable-stayed bridge according to any one of claims 1 to 2.
A cable-stayed bridge that is arranged near the center of the bridge girder and has a vertical girder that connects the lower horizontal ribs adjacent to each other in the direction of the bridge axis. A cable-stayed bridge according to any one of claims 1 to 3.
The lower horizontal rib has a lower flange of the lower horizontal rib and
A cable-stayed bridge characterized by having a lower concrete plate bridge supported by the lower flange of the lower horizontal rib. A cable-stayed bridge according to any one of claims 1 to 4.
At least a part of the lower lateral ribs arranged near the position where the cable is connected to the main girder is formed by stretching I-shaped steel between the main girders.
The lower horizontal ribs arranged at positions other than the vicinity of the connection position of the cables are cable-stayed bridges characterized by having a truss structure in which shaped steel is used as a diagonal member. A cable-stayed bridge according to any one of claims 1 to 5.
A cable-stayed bridge characterized in that a wind shield plate is provided at least within a predetermined distance from the lower part of the main girder toward the center of the bridge girder in the width direction. The method for constructing a cable-stayed bridge according to any one of claims 1 to 5.
A process of extending the main girders on both sides of the width of the bridge girder from the existing bridge girder portion by a predetermined distance, respectively.
The process of connecting the lower horizontal rib between the main girders and
The process of connecting vertical girders between the above lower horizontal ribs adjacent to each other in the bridge axis direction,
In the vicinity of the main girder, a step of connecting the upper horizontal rib and the deck plate to the upper part of the lower horizontal rib, and
The process of connecting the cable to the extended main girder and
A step of connecting the other upper horizontal rib and the deck plate to the upper part of the lower horizontal rib between the upper horizontal rib and the deck plate connected to the upper part of the lower horizontal rib in the vicinity of the main girder. When,
A method of erection of a cable-stayed bridge, which is characterized by having.

Images