JPH07207619A - Main tower of long bridge provided with laterally extended beam and side cable - Google Patents

Abstract

PURPOSE:To stabilize a long bridge against wind load and reduce the weight, by supporting beams laterally extended from the main tower by support cables and supporting and fixing side cables by the laterally extended beams. CONSTITUTION:Laterally stretched beams 11... laterally extending from both right and left side faces of the mast of the main tower 3 of a long bridge are provided. And the beams 11 laterally stretched to the right and left sides are suspended by cables 16, 16 for the laterally stretched beams through the main tower 3. Next, side support saddles 13, 13 or side anchors are provided to support/fix the side cables 9... with the laterally stretched beams 11. In this way, the wind load is supported by a cable system chiefly made of the side cables 9, a long span bridge can be constructed with less steel materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main tower and a cable used for a long bridge and a super long bridge.

[0002]

2. Description of the Related Art Conventionally, main towers used for bridges support the weight of bridge girders through cables and support the vertical load thereof, such as the support of main cables in suspension bridges and the support of cables in cable-stayed bridges. It is a structure that has the function of transmitting to the lower structure, and vertical compressive force acts on the main tower.

Further, as a measure to prevent the shaking of the bridge girder,
There is an arched storm cable (storm rope) below the bridge girder.

The above-mentioned storm cable is generally used for the purpose of improving the wind resistance stability of the main rope at the time of installation. (For example, Patent Publication, 1990-5924.
5, construction method of storm rope, etc. )

Furthermore, as a measure against wind resistance, a grating which is an opening is provided as a measure for increasing the lateral rigidity of the girder.
There are truss girders.

[0006]

As the external force acting on the bridge girder when the long bridge and the ultra-long bridge are bridged, the wind load becomes the most dominant load as the span becomes longer. In particular, it is necessary to increase the lateral rigidity and torsional rigidity of bridge girders in order to deal with the lateral wind load and the external torsional force that can cause disintegrated self-excited vibration due to the wind. This has been dealt with by designing the cross section of the girder as a large cross section and increasing the second moment of area of each girder to increase the lateral rigidity and torsional rigidity of the bridge girder itself.

However, in such conventional methods and structural forms, stiffening girders and box girder structures with a large cross section are prepared, and furthermore, the girders and box girders are pulled in the bridge axis direction. Since no force is applied, a compressive force is always applied to one end of the stiffening girder or box girder when a lateral bending force is applied by wind or the like. Generally, many steel trusses are used as a girder for long bridges, but iron is weak against compressive force, so if one receives excessive lateral bending stress, one end will buckle. The box girder is also generally made of steel, but it is weak against the compressive force in the bridge axial direction. In order to prevent this, it is necessary to take advantage of the characteristics of iron that is strong in tensile force, and therefore it is effective to apply pre-stressing tension to stiffening girders and box girders, but until now, it has been necessary to use individual blocks. Due to problems in the construction method, such as erection while suspending the bridge girder, such consideration was not taken. Therefore, since the lateral load and torsional vibration were dealt with only by increasing the second moment of area of the girder, the cross section inevitably became large and the bridge girder became heavier and, as a result, the tension of the cable for hanging the girder was pulled. There is a problem that the limit length of the span is shortened due to the limit of strength.

Further, in order to suppress / prevent the shaking of the bridge girder,
A storm cable (wind resistant rope-storm rope) may be installed. This storm cable is generally provided temporarily when the bridge section is being erected. Storm cable fasteners are installed on the main tower. Therefore, since the distance between the left and right storm cables is maximum and can be taken only by the width of the main tower, the distance between the left and right storm cables becomes short, and it effectively acts against the lateral wind load and torsional vibration. There was a problem not to do.

In order to solve the above problems, the present invention provides
A type of main tower and cable that has stronger rigidity against lateral wind load and torsional vibration due to wind, etc., and has a lighter girder weight, and can extend the limit length of long bridges more than ever Is intended.

[0010]

[Means for Solving the Problems] In a main tower of a bridge, a side support saddle portion or a side provided on the horizontal projection beam portion is provided, which is provided with a lateral overhang portion which laterally extends from a side surface of a mast of the main tower. Side cables are supported or fixed by anchors and stretched horizontally between the main towers.

In the above description, when the side support saddle is provided on the laterally projecting slag portion, anchor rages are provided on both banks in order to obtain tension of the side cable.

The side cable and the bridge girder main body are connected by a connecting cable or a connecting frame, and the side cable and the bridge girder are integrated so that the side cable shares a considerable portion with respect to a lateral or twisting force.

[0013] In the main tower of the bridge tower, a horizontally projecting leech part which laterally overhangs from the side surface of the mast of the main tower is provided, and the horizontally projecting beam portions are laterally overhanging via the main tower by means of a leech support cable. Hang.

The laterally projecting beam portion is formed of an arch member so that the laterally projecting beam portion can maintain its strength by an arch action in the direction of a force for pulling or supporting the side cable. Alternatively, the lateral overhanging grove portion is formed of a truss member so that the lateral overhanging beam portion can similarly retain its strength by the truss action.

[0015]

The side cables are cables that are stretched horizontally on the left and right sides between the main towers or over the entire length of the bridge, and are tensioned with high tension. The bridge girder is connected to this side cable with a connecting cable or a connecting frame stretched in the direction perpendicular to the bridge axis to be integrated.
Therefore, although the strained side cable contributes significantly to the lateral rigidity of the bridge girder, the side cable should be installed at a considerable distance from the center position of the bridge (for calculating the lateral moment of inertia of the cross section). Moreover, since it is stretched with a high tension, it has a function of significantly increasing the second moment of area and significantly increasing the lateral rigidity of the integral structure.

Regarding the increase in lateral rigidity due to the side cable, the cross section 2 is obtained when the side cable is located at a distance from the center of the bridge axis.
This is more effective because the second moment increases with the square of the distance. For that purpose, it is necessary to make the distance larger than the width of the main tower, but in the present invention, the distance between the side cables is considerably larger than the width of the main tower because the horizontal tower is provided in the main tower. It can be taken for a long time.

In order to increase the distance between the side cables stretched to the left and right, it is necessary to further lengthen the overhanging length of the lateral overhanging beam portion and to firmly support the side cables or to tighten and fix them. is there. Therefore, if the lateral projecting beam portion is formed into a truss structure or an arm structure, the rigidity of the projecting portion can be effectively increased. In addition, by connecting the laterally-extended leech parts that are jutting out from both sides of the main tower through the main tower with the laterally-extended leech part support cables, the laterally-extended leech parts that are extended over a longer period can be connected. It is possible to form a part.

The side cables are stretched between the spans but must be supported by the main tower. Now, the main function of the main tower is to support the vertical load of the entire girder by supporting the main cable. In the main bridge type where side cables are stretched, it is necessary to support and tension the side cables in addition to the main cable as the function of the main tower. The laterally projecting beam portion provided in the main tower has a function of supporting the weight of the side cable. In addition, the horizontal overhanging beam portion provided on the main tower increases the distance between the side cables to increase the lateral moment of inertia of the girder cross section that the side cables integrate with the bridge girder, increasing lateral rigidity and torsional rigidity. Has the function of increasing

As a method of tensioning the above side cable,
There are methods to stretch the side cables only between the main towers and to stretch the entire length of the bridge. In the above description, it is necessary to provide side anchors on the horizontally projecting lees of the main tower so as to not only support the weight of the side cables but also to provide tension to fix the side cables. In addition, in the postscript, at the same time as supporting the own weight of the side cable by installing a saddle on the overhang of the main tower,
Anchorage is provided on both banks to fix the side cables.
I need to be nervous.

By fixing the side cables with anchorages on both banks and tensioning the side cables, the tension of the side cables can be maximized. Therefore, when a lateral load is applied, The tension force makes it possible to prevent the compressive force from acting, which has the effect of increasing the rigidity in the lateral direction.

Further, even when the self-excited vibration is generated in the bridge girder due to the wind load and the torsional load is applied to the bridge girder, the tensioned side cables give the integrated bridge girder a high torsional rigidity. It can be dealt with effectively. When not only the side cables but also the storm cables are installed together, the synergistic effect has a function of significantly increasing the lateral rigidity and the torsional rigidity of the girder.

[0022]

EXAMPLES Examples will be described with reference to the drawings. In FIG. 1, there is a strait 2 between shores 1. A main tower 3 stands on the strait 2 and supports a bridge girder (rigging girder) 5 via a main cable 4 and a hanger 6. The main tower 3 has an A shape in a cross section perpendicular to the bridge axis, and the main cable 4
There is only one and anchor rage 7 installed on both banks
It is fixed and tense. Side cable 9 is the main tower 3
It is supported by the side support saddles 13 installed on the laterally projecting beam portion 11 provided on the shore, and is fixed and tensioned by the anchor rages 7 installed on both banks. In this embodiment, the anchor rage 7 for fixing the main cable 4 and the side cable 9 is a common anchor rage,
Of course, it is possible to use them separately. The connecting cable / connecting frame 10 connects the side cable 9 to the bridge girder (stiffening girder) 5 and the storm cable 14 to the bridge girder (stiffening girder) 5. The storm cable 14 is installed below the bridge girder (rigging girder) 5 to prevent movement / vibration of the bridge girder (rigging girder) 5 which is lifted by wind or the like to move upward.

The embodiment shown in FIG. 2 will be described. There is a strait 2 between the shores 1. A main tower 3 stands on the strait 2 and supports a bridge girder (rigging girder) 5 via a main cable 4 and a hanger 6. The main cable 4 is tensioned by anchorages 7 installed on both banks. The side cable 9 is a horizontally projecting leech section 11 provided in the main tower 3.
It is tensioned and supported by the side anchors 17 installed at. The connecting cable / connecting frame 10 connects the side cable 9 to the bridge girder (stiffening girder) 5 and the storm cable 14 to the bridge girder (stiffening girder) 5. Further, the storm cable 14 is a cable fixing / supporting portion 15 provided in the main tower 3.
It is fixed and tensioned by and is stretched between the central spans. It is installed below bridge girder (holding girder) 5 and bridge girder (holding girder)
5 is lifted by wind or the like to prevent movement / vibration to move upward.

The embodiment shown in FIG. 3 is an embodiment of a bridge having the same structure as in FIG. 1, and is a plan view of the vicinity of one main tower 3 as seen from above. The main tower 3 is installed on four main tower foundations 8 and has lateral beam portions 11 on the left and right. The laterally projecting beam portion 11 of this embodiment has an arch structure.
A side support saddle 13 is provided on the laterally projecting grout portion 11, and the side support saddle 13 supports the side cable 9. The main cable 4 is supported by the main saddle 12.

The embodiment shown in FIG. 4 is an example of a bridge which has the same structure as in FIGS. 1 and 3, and is a side view of the vicinity of the main tower 3 as seen from the side. The main tower 3 is installed on the four main tower foundations 8 and has laterally overhanging slag sections 11 on the left and right. A side support saddle 13 is provided on the laterally projecting grout portion 11, and the side support saddle 13 supports the side cable 9. The main cable 4 is supported by the main saddle 12. A storm cable 14 is provided in the lower part of the main tower 3, is supported by a cable fixing / supporting portion 15, and is tensioned, and a connecting cable / connecting frame 10 is provided between the storm cable 14 and the bridge girder (rigging girder) 5. Are connected by.

The embodiment shown in FIG. 5 is an embodiment of a bridge sill having the same structure as in FIGS. 1, 3 and 4, and is a cross-sectional view near the main tower 3. The main tower 3 is installed on the four main tower foundations 8 and has laterally overhanging slag sections 11 on the left and right. A side support saddle 13 is provided on the laterally projecting beam portion 11, and the side support saddle 13 supports the side cable 9. The main cable 4 is supported by the main saddle 12. A storm cable 14 is provided at the bottom of the main tower 3,
The tension is supported by the cable fixing / supporting portion 15. Connecting cable / connecting frame 10 is a bridge girder (rigid girder)
5, the storm cable 14 and the side cable 9 are connected. Also, the hanger 6 is the main cable 4
The bridge girder (rigging girder) 5 is hung by. A connecting cable / connecting frame 10 is connected between the storm cable 14 and the bridge girder (rigging girder) 5.

The embodiment shown in FIG. 6 is an embodiment of bridge sill having the same structure as in FIGS. 1, 3, 4 and 5, and the main tower 3
It is a perspective view of the vicinity. The main tower 3 is installed on the four main tower foundations 8 and has laterally overhanging slag sections 11 on the left and right. A side support saddle 13 is provided on the laterally projecting grout portion 11, and the side support saddle 13 supports the side cable 9. The main cable 4 is supported by the main saddle 12. The storm cable 14 is supported by a cable fixing / supporting portion 15 provided in the lower part of the main tower 3 and is strained. The connecting cable / connecting frame 10 connects the bridge girder (rigging girder) 5, the storm cable 14 and the side cable 9. Further, the hanger 6 suspends the bridge girder (rigging girder) 5 by the main cable 4. A connecting cable / connecting frame 10 is connected between the storm cable 14 and the bridge girder (rigging girder) 5.

The embodiment shown in FIG. 7 is an example of a bridge in which the main tower 3 is a gate type, and is a perspective view thereof. The main cables 4 are installed on the left and right. A bridge girder (rigging girder) 5 is supported by a connecting cable / connecting frame 10. The main tower 3 is installed on four main tower foundations 8 and has lateral beam portions 11 on the left and right. A side support saddle 13 is provided on the laterally projecting beam portion 11, and the side support saddle 13 supports the side cable 9. The main cable 4 is supported by the main saddle 12. The connecting cable / connecting frame 10 connects the bridge girder (rigging girder) 5 and the side cable 9. Further, the hanger 6 suspends the side cable 9. The bridge girders (capture {u girders) 5 are connected by a connecting cable / connecting frame 10.

The embodiment shown in FIG. 8 is an embodiment in which the main tower 3 is a gate-shaped bridge, and is a cross-sectional view near the main tower 3,
In this case, unlike the sixth embodiment, the storm cable 14 is installed. Main cables 4 are installed on the left and right. Bridge girder (capture girder) 5 connecting cable / connecting frame 1
0 supports it. The main tower 3 is installed on the four main tower foundations 8 and has laterally overhanging slag sections 11 on the left and right. The horizontal overhanging section 11 installed on the left and right of the main tower 3 is hung by the horizontal overhanging section support cables 16 connecting the horizontal overhanging beam sections 11 via the main tower 3. A side support saddle 13 is provided on the laterally projecting beam portion 11, and the side support saddle 13 supports the side cable 9. The main cable 4 is supported by the main saddle 12. A storm cable 14 is supported and strained by a cable anchoring / supporting portion 15 provided at the bottom of the main tower 3. The connecting cable / connecting frame 10 connects the bridge girder (rigging girder) 5, the storm cable 14 and the side cable 9. Further, the hanger 6 suspends the bridge girder (rigging girder) 5 by the main cable 4.

[0030]

Since the present invention is constructed as described above, it has the following effects.

As the span between the main towers becomes longer, the wind load that becomes more dominant as an external force is shared by the cable system centering on the side cables in the structure of the present invention. High tension is applied to the side cable in advance, so that the load due to external force such as wind load can be efficiently shared. So you get a very long span bridge with less steel material. The lateral stiffness of the bridge girder can be significantly increased without increasing the weight of the bridge girder, thus effectively addressing the wind loads that must be considered most in the design of long bridges and forming longer span bridges. It becomes possible to do. That is, according to the bridge type of the present invention, it is possible to construct a super-long bridge, which cannot be obtained by a conventional cable-stayed bridge or suspension bridge, and it is possible to make the span of the bridge extremely long.

As described above, since the material is effectively used, it is possible to reduce the construction cost of the entire bridge even if the amount of steel material used is small. Also, since the self-weight can be reduced, not only the construction cost of the upper construction can be saved, but also the load on the tower can be reduced, the self-weight of the supporting bridge girder can be relatively light, and the cost of the lower construction can be reduced. You can Since the materials will be used effectively, less steel will be used and the construction cost of the entire bridge can be reduced. Furthermore, since the span can be taken longer, in the case of a bridge that crosses the strait, a small number of piers will suffice, and construction costs will be low.

With respect to the wind, in the bridge girder type using the main tower and side cables of the present invention, most of the main structure is formed as an open structure, so the wind blows through and the external force of the wind is applied. Is greatly reduced. Therefore,
The wind load can be significantly reduced, and a bridge with less shaking is formed even under normal conditions. There is little shaking due to the wind, and it is advantageous for maintenance and a stable bridge can be used.

The main tower provided with the side cable and the main cable, the upper and lower connecting cables / connecting frames for connecting the side cable and the storm cable and the bridge girder, and the laterally projecting sill portion provides a design which has never been seen before. In short, this type of bridge requires three-dimensional design, so there are many variations in the design at once, and the design parameters such as the length of the lateral beam and the set height of the side cable are also increased. Since the design tolerance is wide, flexible and optimal design can be performed by incorporating the characteristics of various regions. In addition, although bridges have become valuable as cultural assets in recent years, the bridge form of the present invention makes it possible to provide a completely new aesthetic appearance of bridges.

[Brief description of drawings]

FIG. 1 is a view showing a main tower having a laterally projecting beam portion, a side cable, and a side support saddle for supporting the side cable provided on the laterally projecting beam portion of the main tower, and an anchorage for fixing and tensioning the side cable. It is a perspective view of the whole bridge type.

FIG. 2 is an overall perspective view of a bridge type of the present invention in which a main tower having a laterally projecting beam portion, a side cable, and a side anchor for supporting / fixing / tensioning the side cable are provided on the laterally projecting beam portion.

FIG. 3 is a plan view seen from above in the vicinity of the main tower of the bridge type of the present invention.

FIG. 4 is a plan view seen from a side surface near a main tower of the bridge type of the present invention.

FIG. 5 is a cross-sectional view near the main tower of the bridge type of the present invention.

FIG. 6 is a perspective view of the vicinity of a bridge type main tower of the present invention.

FIG. 7 is a perspective view near a main tower of a bridge whose main tower is a gate type.

FIG. 8 is a cross-sectional view in the vicinity of the main tower of an embodiment of a bridge whose main tower is a gate type.

[Explanation of symbols]

 1 shore 2 strait 3 main tower 4 main cable 5 bridge girder (holding girder) 6 hanger 7 anchorage 8 main tower foundation 9 side cable 10 connecting cable / connecting frame 11 side overhanging beam 12 main saddle 13 side support saddle 14 storm cable 15 Cable anchoring / supporting part 16 Horizontal overhanging beam supporting cable 17 Side anchor

Claims (5)

[Claims] 1. A bridge tower main tower is provided with a laterally projecting leash part projecting outward from the side surface of the mast of the main tower in a direction perpendicular to the bridge axis and outside, and the side cable is supported / fixed by the horizontally projecting leech part. A long bridge main tower equipped with a laterally projecting beam, which is equipped with side support saddles or side anchors. 2. A bridge tower main tower is provided with lateral projecting bar sections that laterally project from the side surface of the mast of the main tower, and the lateral projecting beam sections projecting to both left and right sides are provided through the main tower. A long bridge having a laterally extending beam portion, which is provided with a side support saddle or a side anchor for suspending and supporting the laterally extending beam portion supporting cable and supporting / fixing the side cable at the laterally extending beam portion. Main tower. 3. The main tower of a long bridge having a lateral beam portion according to claim 1 or 2, wherein the laterally projecting grout portion has an arch structure or a truss structure. 4. A side cable which is fixed to a side anchor provided in the lateral overhanging section according to any one of claims 1 to 3 and which is horizontally stretched between main towers. 5. A side cable supported by a side support saddle provided on the laterally projecting beam portion according to claim 1, stretched horizontally in the entire span, and fixed to an anchor rage. .