JP3130509B2 - Tower suspension displacement type multi span suspension bridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-span suspension bridge with suppressed top displacement, and more particularly, to effectively utilizing a main cable and a stiffening girder to suppress a top displacement of an intermediate tower caused by an unbalanced external force. The construction cost can be significantly reduced.

[0002]

2. Description of the Related Art Suspension bridges generally have a pair of main towers.
It is roughly classified into a span suspension bridge and a multi-span suspension bridge having four or more spans having a pair of side towers and one or more intermediate towers. Most of the suspension bridges being constructed are three-span suspension bridges, but in three-span suspension bridges, the main cable becomes thicker as the total length of the suspension bridge increases.
Construction costs also increase. In a multi-span suspension bridge, even if the overall length of the suspension bridge becomes longer, the main cable does not become thicker in accordance with the length, but external forces (wind load, live load, etc.) acting unequally across multiple spans As a result, a large bending moment acts on the intermediate tower, so that the construction cost of the conventional multi-span suspension bridge is higher than that of the three-span suspension bridge.

[0003] The conventional multi-span suspension bridge will be described. As shown in Figs.
For example, 1 is installed vertically in the vicinity of both ends in the bridge axis direction.
A pair of side towers 31, an intermediate tower 32 erected between the pair of side towers 31, a top 31 a of the pair of side towers 31 and an intermediate tower 3
And a main cable 34 for continuously connecting the second tower top 32a to the anchorages 33 at both ends of the suspension bridge. The main cable 34 is curved in a catenary line between the tower top 31a and the tower top 32a.

[0004] Stiffening girders 36 are horizontally arranged between the side tower 31 and the intermediate tower 32 and between the side tower 31 and the anchorage 33, respectively. It is at a height position in the middle of the height direction of the intermediate tower 31 and the intermediate tower 32. These stiffening girders 36 are hung on hangers 34 a suspended at predetermined intervals from the main cable 34, and the ends of the stiffening girders 36 are connected to the corresponding side tower 31 via a tower link 35.
Alternatively, the stiffener girder 36 is connected to and suspended from the intermediate tower 32, and the stiffening girder 36 can be horizontally moved to some extent in the bridge axis direction via the tower link 35. The land-side ends of the stiffening girders 36 at both ends are supported by rollers, and are configured to be movable in the bridge axis direction.

[0005]

[Problems to be Solved by the Invention] The above-mentioned multi-span suspension bridge 3
At 0, the top 31a of the side tower 31 is connected to the anchorage 33 by the main cable 34 and is sufficiently restrained. However, the main cables on both sides of the top 32a of the intermediate tower 32 are curved in a catenary line and have low binding performance. Due to the live load, the top 3 of the intermediate tower 32
The displacement of 2a increases to one side, and a large bending moment acts on the intermediate tower 32, and particularly, the bending moment acting on the tower base of the intermediate tower 32 becomes abnormally large.

As a result, the bending of the stiffening girder 36 between the intermediate towers 32 and the side towers 31 becomes large, which is not preferable in terms of stable running of vehicles and trains. Therefore, in order to reduce the displacement of the top 32a of the intermediate tower 32, the intermediate tower 3
Although measures such as increasing the cross section of 2 to increase rigidity are conceivable, the size of the intermediate tower 32 is remarkably increased, the construction cost becomes huge, and economic efficiency is lacking.

Therefore, for example, Japanese Patent Application Laid-Open No. 1-287304
In the multi-span suspension bridge described in the publication, a small sag top cable connecting the tower tops and connecting those towers to the anchorage is installed in addition to the main cable,
A technique is described in which the top cable is strongly restrained by the top cable to suppress displacement of the top of the intermediate tower. However, in the multi-span suspension bridge provided with this top cable, the construction cost is high because the top cable from the top of one tower to the top of the other tower must be installed in addition to the main cable. And lacks economy.

SUMMARY OF THE INVENTION An object of the present invention is to significantly reduce the top displacement of an intermediate tower without significantly increasing the construction cost of a multi-span suspension bridge, to significantly reduce the load conditions of the intermediate tower, and to reduce the bending moment of the tower base. To prevent the intermediate tower from being enlarged, and to reduce the deflection of the stiffening girder between the intermediate supports,
And so on.

[0009]

According to the first aspect of the present invention, there is provided a multi-span suspension bridge with a suppressed top displacement, wherein at least one bridge is provided between a pair of vertical side towers.
In a multi-span suspension bridge with a vertical intermediate tower,
A main cable connecting the tops of the pair of side towers and the top of the intermediate tower to the anchorages at both ends of the suspension bridge; and a main cable that is hung by a hanger and continuous to be able to transmit a load in the bridge axis direction. One continuous stiffening girder, a coupling mechanism for connecting the middle part of the continuous stiffening girder to the side tower and the intermediate tower, and a connecting means for connecting at least one end of the continuous stiffening girder to a corresponding anchorage In the intermediate span between the intermediate tower and the side tower or the intermediate tower, a center portion of the main cable between the spans is connected to a continuous stiffening girder so that a load can be transmitted. Here, at least one between a pair of side towers
Although an intermediate tower is provided, a plurality of intermediate towers may be provided.

When non-uniform external force (unbalanced live load, non-uniform wind load, etc.) acts between the intermediate supports on both sides of the intermediate tower on the tower displacement suppressing type multi-span suspension bridge, both sides of the intermediate tower are affected. Due to the difference in the tension of the main cable, the top of the intermediate tower tries to displace to one side in the bridge axis direction. However, one continuous stiffening girder continuous to be able to transmit a load in the bridge axis direction is provided, and at least one end of the continuous stiffening girder is connected to the corresponding anchorage by the connecting means, so that the continuous stiffening girder is provided. The girder does not displace in the bridge axis direction and keeps a substantially constant position in the bridge axis direction. In addition, in the middle section between the intermediate tower and the side tower or the intermediate tower, the central part of the main cable is connected to the continuous stiffening girder so that the load can be transmitted in the bridge axis direction. The middle part of the span
Maintains a nearly constant position without displacement in the bridge axis direction.

In other words, even if the top of the intermediate tower is displaced to one side in the bridge axis direction, the main cable and the continuous stiffening girder restrain it, so that the tension difference of the main cable on both sides of the intermediate tower increases. There is no significant displacement of the top of the intermediate tower in the bridge axis direction. As a result, the bending of the stiffening girder portion between the intermediate supports is kept small, and the bending moment acting on the intermediate tower is significantly reduced. Therefore, it is not necessary to use an extremely high rigidity intermediate tower. In this way, the construction cost of the intermediate tower and its basic structure can be significantly reduced, and since it is not necessary to add a large-sized member, the construction cost of the multi-span suspension bridge can be significantly reduced.

[0012] The multi-span suspension bridge with suppressed tower top displacement according to claim 2 is
In a multi-span suspension bridge having at least one vertical intermediate tower erected between a pair of vertical side towers, the top of the pair of side towers and the top of the intermediate tower are connected at both ends of the suspension bridge. A main cable connected to the anchorage, a plurality of stiffeners suspended from the main cable by hangers and connected to be able to transmit a load in the bridge axis direction, and a side tower corresponding to an end of each stiffener. Or a coupling mechanism coupled to the intermediate tower, and coupling means for coupling at least one end of the plurality of stiffening girders to a corresponding anchorage, between the intermediate tower and the intermediate tower between the side tower or the intermediate tower, The central part of the span of the cable is connected to the stiffening girder so that the load can be transmitted in the bridge axis direction.

Although the stiffening girder is not a single continuous structure,
Since the plurality of stiffening girders are connected so that a load can be transmitted in the bridge axis direction, the stiffening girders function similarly to the continuous stiffening girder of the first aspect. And since at least one end of the plurality of stiffening girders is connected to the corresponding anchorage by the connecting means,
The plurality of stiffening girders are constrained to hardly move in the bridge axis direction, similarly to the continuous stiffening girder of claim 1. In the same manner as in the first aspect, between the intermediate tower and the side tower or the intermediate support between the intermediate towers, a central portion of the main cable between the supports is connected to the stiffening girder so that a load can be transmitted in the bridge axis direction.

Therefore, this tower top displacement suppressing type multi-span suspension bridge basically has the same effect as the multi-span suspension bridge of the first aspect. As a result, even when an uneven external force (such as an unbalanced live load) acts on both sides of the intermediate tower, the bending of the stiffening girder between the intermediate supports is kept small, and the bending moment acting on the intermediate tower is maintained. Also becomes extremely small, so that it is not necessary to apply an extremely high rigidity as the intermediate tower. And since the construction cost of the intermediate tower and its base structure can be significantly reduced and there is almost no need to add large-sized members,
The construction cost of the multi-span suspension bridge can be significantly reduced.

According to a third aspect of the present invention, there is provided a multi-span suspension bridge for suppressing top displacement.
In a multi-span suspension bridge having at least one vertical intermediate tower erected between a pair of vertical side towers, the top of the pair of side towers and the top of the intermediate tower are connected at both ends of the suspension bridge. A main cable connected to the anchorage, a plurality of stiffening girders suspended from the main cable by hangers, and an end of each stiffening girder disposed between the intermediate supports is provided in a corresponding side tower or intermediate tower. A coupling mechanism for coupling, wherein a central portion of the main cable between the intermediate tower and the side tower or the intermediate tower is connected to the stiffening girder so as to be able to transmit a load in the bridge axis direction. It is assumed that.

This multi-span suspension bridge with suppressed tower top displacement is made by paying attention to the fact that a pair of side towers are firmly restrained by an anchorage by a main cable. For the stiffening girder, the same configuration as the conventional three-span suspension bridge can be applied. Since the end of each stiffening girder disposed between the intermediate supports is connected to the side tower or the intermediate tower by a coupling mechanism, and the pair of side towers is strongly restrained by the main cable to the anchorage, A plurality of stiffening girders other than a pair of stiffening girders on both sides are restrained so as to hardly move in the bridge axis direction.

In the intermediate span between the intermediate tower and the side tower or the intermediate tower, the central portion of the main cable is connected to the stiffening girder so that the load can be transmitted in the bridge axis direction. The suspension bridge basically has the same function as the first aspect. As a result, even when an uneven external force (such as an unbalanced live load) acts on both sides of the intermediate tower, the bending of the stiffening girder between the intermediate supports is kept small, and the bending moment acting on the intermediate tower is maintained. Also becomes extremely small, so that it is not necessary to apply an extremely high rigidity as the intermediate tower. And
The construction cost of the intermediate tower and its basic structure can be significantly reduced, and it is not necessary to add a large-sized member. Therefore, the construction cost of the multi-span suspension bridge can be significantly reduced.

[0018] According to the fourth aspect of the present invention, there is provided a multi-span suspension bridge for suppressing top displacement.
The invention according to claim 1, wherein a thermal deformation absorbing mechanism capable of absorbing thermal deformation is interposed between the continuous stiffening girder connected to the anchorage and the anchorage. One end of the continuous stiffening girder is connected to a corresponding anchorage by a connecting means, and a thermal deformation absorbing mechanism absorbs thermal deformation (thermal expansion or thermal contraction) of the stiffening girder. The thermal deformation absorbing mechanism is mainly composed of, for example, an oil damper (also referred to as a dash pod). When an external force acts at a normal speed, the thermal deformation absorbing mechanism exerts a restraining action, and is slow in time such as thermal deformation. It shall be configured so as not to exert a restricting effect on the change.

[0019] The tower displacement control type multi span suspension bridge of claim 5 is
The invention according to claim 2 is characterized in that a thermal deformation absorbing mechanism is interposed between the stiffening girder connected to the anchorage and the anchorage. At least one end of each of the plurality of stiffening girders is connected to the anchorage by the connecting means, but the thermal deformation absorbing mechanism absorbs thermal deformation (thermal expansion and thermal contraction) of the stiffening girders. It is.

According to a sixth aspect of the present invention, there is provided a multi-span suspension bridge for suppressing top displacement.
The invention according to claim 3 is characterized in that the coupling mechanism has a thermal deformation absorbing mechanism capable of absorbing thermal deformation. When the stiffening girder is thermally deformed, it receives thermal stress.
In order to prevent this, the coupling mechanism is provided with a thermal deformation absorbing mechanism capable of absorbing thermal deformation.

According to a seventh aspect of the present invention, there is provided a multi-span suspension bridge for suppressing top displacement.
The invention according to any one of claims 4 to 6, wherein the thermal deformation absorbing mechanism comprises an oil damper. The oil damper acts as an unconstrained change over time, such as thermal deformation, and acts as a constraint on changes that are not slow over time. Therefore, the oil damper is suitable as a thermal deformation absorbing mechanism.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. The tower top displacement suppression type multi span suspension bridge of this embodiment corresponds to the tower top displacement suppression type multi span suspension bridge of claim 2. As shown in FIG. 1, a tower displacement suppressing type multi-span suspension bridge 1 according to an embodiment of the present invention includes a pair of side towers 2 erected vertically near both ends in the bridge axis direction,
An intermediate tower 3 erected vertically at an intermediate point between the pair of side towers 2, connecting the top 2 a of the pair of side towers 2 and the top 3 a of the intermediate tower 3 with , These tower tops 2a, 3a
And two main cables 5 for connecting the two to the anchorages 4 on both banks. These main cables 5 are curved in a catenary line between the intermediate towers between the side tower 2 and the intermediate tower 3, and a central portion of the intermediate span between the intermediate towers reaches near the upper surface of the stiffening girder 7.

As shown in FIGS. 1 and 2, between the side tower 2 and the intermediate tower 3 and between the side tower 2 and the anchorage 4, stiffening girders 7 are disposed in a horizontal posture, respectively. These four stiffening girders 7
Are arranged substantially in series and are located at a height level in the middle of the side tower 2 and the intermediate tower 3 in the height direction. Hangers 5a are suspended from the two main cables 5 at predetermined small intervals, and each stiffening girder 7 is suspended by a plurality of hangers 5a. A bracket 6a and a tower link 6b are provided at the middle of the side tower 2 and the middle tower 3 in the height direction as a connecting mechanism 6 for connecting the end of the stiffening girder 7 to the middle of the side tower 2 and the middle tower 3 in the height direction. Are provided, and the end of each stiffening girder 7 is provided with a corresponding tower link 6.
b is connected to the pin b via a bracket 6c. The ends of the adjacent stiffening girders 7 are connected by a link-like connecting member 7c and a pin member 7d so that a load can be transmitted in the bridge axis direction.

As shown in FIGS. 1 and 3, the land side end of the stiffening girder 7a on both sides is supported by rollers on the anchorage 4 and the land side end of the stiffening girder 7a is connected. For example, it is connected to the anchorage 4 by a pair of oil dampers 8 (which are also oil dampers 8 as a thermal deformation absorbing mechanism) as means. The oil damper 8 is not constrained with respect to a temporally slow change such as thermal deformation, and exerts a constraining force against a dynamic external force such as a live load or a wind load.

As shown in FIG. 4, in the intermediate section between the intermediate tower 3 and the side tower 2, the central portion between the main cables 5, that is, the lowermost part, is stiffened via a pair of center stay cables 9. It is connected to the girder 7b (the stiffening girder 7 between the intermediate supports) so that the load can be transmitted in the bridge axis direction. This is to enhance the restraining action on the top 3a of the intermediate tower 3 via the stiffening girder 7 and the main cable 5. However, the structure of FIG. 5 may be adopted instead of the structure of FIG. In the structure shown in FIG. 5, in the middle span between the intermediate tower 3 and the side tower 2, the center between the spans of the main cables 5, that is, the lowermost part, is connected to the stiffening girder 7 b via the connecting fitting 9 A in the bridge axis direction. It is connected so that the load can be transmitted. The connection fitting 9A may be welded to the stiffening girder 7b, or may be fixed with a plurality of bolts or the like.

Next, the operation of the tower top displacement suppressing type multi-span suspension bridge 1 will be described. The four stiffening girders 7 are arranged in series and connected by a connecting member 7c and a pin member 7d so that a load can be transmitted in the bridge axis direction. The roller is supported by the college 4 and is connected to the college 4 by an oil damper 8. Therefore, the thermal deformation of the four stiffening girders 7 is surely absorbed by the oil damper 8, but when an external force such as a live load or a wind load acts, the oil damper 8 exerts a restraining force and exerts a restraining force. Both ends of the two stiffening girders 7 are restrained with respect to the carriage 4. Thus, the four stiffening girders 7 always maintain a substantially constant position without moving in the bridge axis direction.

In addition, since the central portion (lowermost portion) of the main cable 5 is connected to the stiffening girder 7b so as to transmit a load in the bridge axis direction, the main cables 5 on both sides of the intermediate tower 3 are provided. However, the center portion of the span does not move in the bridge axis direction. Therefore, the intermediate tower 3
The main cables 5 on both sides of the intermediate tower 3 are constrained to hardly move in the bridge axis direction even if an uneven external force (live load, wind load, etc.) acts on both sides of the intermediate tower 3. The tower top 3a hardly moves in the bridge axis direction.

As described above, the ability to restrain the top 3a of the intermediate tower 3 via the main cable 5, the four stiffening girders 7 capable of transmitting a load in the bridge axis direction, and the oil damper 8 is enhanced. The load condition of the intermediate tower 3 was remarkably relaxed.
Is extremely small. Therefore, the rigidity of the intermediate tower 3 can be significantly reduced as compared with the conventional multi-span suspension bridge, the cross-section can be reduced, and the overall weight can be reduced, and the cost of constructing the intermediate tower 3 and its basic structure can be significantly reduced. Can be reduced. Also, the deflection of the stiffening girder 7 due to uneven external force on both sides of the intermediate tower 3 is significantly reduced, so that stable running of a vehicle or the like is also improved. The above operations and effects can be achieved without adding a large-sized member, so that the construction cost of the multi-span suspension bridge 1 can be significantly reduced.

Next, a modified embodiment in which the tower top displacement suppressing type multi-span suspension bridge 1 is partially modified will be described. However, the same members as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. 1] Multi-span suspension bridge 1A shown in FIGS. 6 and 7
The connecting member 7c and the pin member 7d for connecting the ends of the stiffening girders 7 are omitted, and the end of each stiffening girder 7 is connected to the corresponding side tower 2 or intermediate tower 3 via the coupling mechanism 6. At the same time, the end of each stiffening girder 7 is connected to the corresponding side tower 2 or intermediate tower 3 via an oil damper 11 functioning as a thermal deformation absorbing mechanism. The other parts are the same as those of the multi-span suspension bridge 1, and the same components as those of the multi-span suspension bridge 1 are denoted by the same reference numerals and description thereof is omitted. Since the oil damper 11 exerts a restraining action against a normal speed change and does not exert a restraining action against a slow change such as thermal deformation, the tower top displacement suppressing type multi-span suspension bridge 1A Has basically the same action as the tower displacement control type multi-span suspension bridge 1.

2] The tower top displacement suppressing type multi-span suspension bridge 1B shown in FIGS. 8 and 9 corresponds to the tower top displacement suppressing type multi-span suspension bridge of claim 3. This tower top displacement control type multi span suspension bridge 1
B has a pair of main cables 5, four stiffening girders 12, a large number of hangers 5a, anchorages 4 on both banks, and the like, as in the case of the tower displacement suppressing type multi-span suspension bridge 1. ing. The structure of the stiffening girder 12a on both sides is the same as that of the conventional multi-span suspension bridge, and the end of the stiffening girder 12a is connected to the side tower 2 by the bracket 10a and the tower link 10b. Have been. The end of the stiffening girder 12b between the intermediate supports is connected to the corresponding side tower 2 or intermediate tower 3 by an oil damper 11 as a coupling mechanism so that a load can be transmitted in the bridge axis direction. Between the intermediate supports, the central portion (lowest portion) of the main cable 5 is connected to the stiffening girder 12b in a structure similar to the structure of FIG. 4 or 5 so as to be able to transmit a load in the bridge axis direction. In addition, the same components as those of the tower top displacement suppressing type multi-span suspension bridge 1 are denoted by the same reference numerals, and description thereof is omitted.

Next, the operation of the tower top displacement suppressing type multi span suspension bridge 1B will be described. This tower top displacement control type multi span suspension bridge 1
B is made by paying attention to the fact that the pair of side towers 2 is firmly restrained to the anchorage 4 by the main cable 5, and for the pair of stiffening girders 12a on both banks,
The same configuration as the conventional three-span suspension bridge is applicable.
The end of each stiffening girder 12b disposed between the intermediate supports is connected to the side tower 2 or the intermediate tower 3 by a connecting mechanism, and the pair of side towers 2 is firmly connected to the anchorage 4 by the main cable 5. Because of the restraint, a plurality of stiffening girders 12b other than the pair of stiffening girders 12a on both banks are restrained so as to hardly move in the bridge axis direction.

In the middle span between the intermediate tower 3 and the side tower 2, the central portion of the main cable 5 is connected to the stiffening girder 12b so that the load can be transmitted in the bridge axis direction. The displacement suppression type multi-span suspension bridge 1B basically operates in the same manner as the tower top displacement suppression type multi-span suspension bridge 1. As a result, even when an uneven external force (such as an unbalanced live load) acts on both sides of the intermediate tower 3, the stiffening girders 12 between the intermediate supports can be used.
Since the bending of b is maintained small and the bending moment acting on the intermediate tower 3 is significantly reduced, it is not necessary to use an extremely high rigidity as the intermediate tower 3. Since the construction cost of the intermediate tower 3 and its basic structure can be significantly reduced, and there is almost no need to add a large-sized member, the construction cost of the tower displacement suppressing type multi-span suspension bridge 1B is significantly reduced. Can be.

[3] A multi-span suspension bridge with a suppressed top displacement corresponding to the multi-span suspension bridge with a suppressed top displacement according to claim 1 will be described. Instead of the four stiffening girders 7 in the tower displacement suppressing type multi-span suspension bridge 1 shown in FIG. 1, one continuous stiffening girder continuous over the entire length as shown in FIGS. A description will be given of a tower top displacement suppressing type multi span suspension bridge 1C employing 7A. The single continuous stiffening girder 7A is hung by the hanger 5a on the main cable 5 and is continuous so that a load can be transmitted in the bridge axis direction. In this case, the middle part of the continuous stiffening girder 7A is connected to the side tower 2 and the intermediate tower 3 via the same coupling mechanism 6 as in the above embodiment. In the middle span, the main cable 5
And the connecting means for connecting at least one end of the continuous stiffening girder 7A to the anchorage is a multi-span of the tower top displacement suppressing type. Same as suspension bridge 1. In addition, the same reference numerals are given to the same components as those of the tower top displacement suppressing type multi-span suspension bridge 1, and the description is omitted.

When non-uniform external force (unbalanced live load, non-uniform wind load, etc.) is applied between the intermediate supports on both sides of the intermediate tower 3, the intermediate tower 3 is controlled. Because there is a difference in the tension of the main cable 5 on both sides of
The top 3a of the intermediate tower 3 is about to be displaced to one side in the bridge axis direction. However, since one continuous stiffening girder is provided so as to be able to transmit the load in the bridge axis direction, and at least one end of the continuous stiffening girder is connected to the corresponding anchorage 4 by the connecting means, the continuous stiffening girder is connected. The rigid girder does not displace in the bridge axis direction and keeps a substantially constant position in the bridge axis direction. In addition, in the intermediate span between the intermediate tower 3 and the side tower 2 or the intermediate tower, the central portion of the main cable 5 is connected to the continuous stiffening girder so that the load can be transmitted. The center part of the span also maintains a substantially constant position without being displaced in the bridge axis direction.

That is, even if the top 3a of the intermediate tower 3 is displaced in one direction in the bridge axis direction, the main cable 5 and the continuous stiffening girder restrict the top 3a. The difference does not increase, and the top of the intermediate tower 3 does not significantly displace in the bridge axis direction. As a result, the bending of the stiffening girder portion between the intermediate supports is kept small, and the bending moment acting on the intermediate tower is significantly reduced. Therefore, it is not necessary to use an extremely high rigidity as the intermediate tower 3.

In this way, the construction cost of the intermediate tower 3 and its basic structure can be significantly reduced, and since there is almost no need to add large-sized members, the construction cost of the tower displacement suppressing type multi-span suspension bridge is significantly reduced. can do.

4) In the above embodiment, the description has been given of the tower displacement suppressing type multi-span suspension bridge provided with one intermediate tower 3.
When the distance between the banks is large, a plurality of intermediate towers may be erected between a pair of side towers. 5] In the tower displacement suppressing type multi-span suspension bridge of FIG. 1, the oil damper 8 is provided only between one end of one of the stiffening girders 7 a and the anchorage 4 among the stiffening girders 7 a on both banks, The other end of the other stiffening girder 7a may be supported by the anchorage 4 only by roller support.

6) A dash pod may be used in place of the oil dampers 8 and 11. Instead of the oil dampers 8, 11 and the dash pod, a temperature sensor for detecting air temperature or the temperature of the stiffening girder is used. A thermal displacement absorbing device that operates to eliminate thermal stress in the bridge axis direction based on the temperature detected by the temperature sensor (for example, a device mainly including a screw mechanism including a nut member and a screen shaft) It is also possible to apply

[0039]

According to the first aspect of the present invention, as described above, even if the top of the intermediate tower is displaced to one side in the bridge axis direction, it is restrained by the main cable and the continuous stiffening girder.
The difference in tension between the main cables on both sides of the intermediate tower does not increase, and the top of the intermediate tower does not significantly displace in the bridge axis direction. As a result, the bending of the stiffening girder portion between the intermediate supports is kept small, and the bending moment acting on the intermediate tower is significantly reduced. Therefore, it is not necessary to use an extremely high rigid intermediate tower.

In this way, the construction cost of the intermediate tower and its basic structure can be significantly reduced, and there is almost no need to add a large-sized member. Therefore, the construction cost of the tower displacement suppressing type multi-span suspension bridge is significantly reduced. be able to.

According to the second aspect of the present invention, as described above,
Although the plurality of stiffening girders are not a single continuous structure, the plurality of stiffening girders are connected so as to be able to transmit a load in the bridge axis direction, and thus function similarly to the continuous stiffening girder of claim 1. . Since at least one end of each of the plurality of stiffening girders is connected to the corresponding anchorage by the connecting means, the plurality of stiffening girders move in the bridge axis direction, similarly to the continuous stiffening girder of claim 1. And always maintain a constant position. This tower top displacement suppressing type multi span suspension bridge basically has the same effect as the tower top displacement suppressing type multi span suspension bridge of claim 1. As a result, even when an uneven external force (such as an unbalanced live load) acts on both sides of the intermediate tower, the bending of the stiffening girder between the intermediate supports is kept small and the bending moment acting on the intermediate tower Also becomes extremely small, so that it is not necessary to apply an extremely high rigidity as the intermediate tower.

Since the construction cost of the intermediate tower and its basic structure can be significantly reduced, and there is no need to add a large-sized member, the construction cost of the tower displacement suppressing type multi-span suspension bridge is significantly reduced. be able to.

According to the invention of claim 3, as described above,
Since the end of each stiffening girder disposed between the intermediate supports is connected to the side tower or the intermediate tower by a coupling mechanism, and the pair of side towers is strongly restrained by the main cable to the anchorage, A plurality of stiffening girders other than a pair of stiffening girders on both banks maintain a constant position without moving in the bridge axis direction. And, in the middle span between the middle tower and the side tower or the middle tower, the center part of the span of the main cable is connected to the stiffening girder so that the load can be transmitted in the bridge axis direction. In the case of a multi-span suspension bridge, the deflection of the stiffening girder between the intermediate supports is basically small even when an uneven external force (such as an unbalanced live load) acts on both sides of the intermediate tower. In addition, the bending moment acting on the intermediate tower is remarkably reduced, so that it is not necessary to apply an extremely rigid intermediate tower. And since the construction cost of the intermediate tower and its basic structure can be significantly reduced, and it is not necessary to add a large-sized member, the construction cost of the tower displacement suppressing type multi-span suspension bridge can be significantly reduced. .

According to the fourth aspect of the present invention, since the thermal deformation absorbing mechanism capable of absorbing thermal deformation is interposed between the continuous stiffening girder connected to the anchorage and the anchorage, the continuous stiffening girder is provided. Even if one end of the stiffener is connected to the corresponding anchorage by the connecting means, the thermal deformation absorbing mechanism can absorb the thermal deformation (thermal expansion or thermal contraction) of the stiffening girder. Other claim 1
It has the same effect as.

According to the fifth aspect of the present invention, since the heat deformation absorbing mechanism is interposed between the stiffening girder connected to the anchorage and the anchorage, at least one end of the plurality of stiffening girder is connected to the connecting means. Claim 4 when connected to the anchorage by
Similarly to the above, the thermal deformation (thermal expansion and thermal contraction) of the stiffening girder can be absorbed by the thermal deformation absorbing mechanism. Other claim 2
It has the same effect as.

According to the sixth aspect of the present invention, since the coupling mechanism has a thermal deformation absorbing mechanism capable of absorbing thermal deformation,
By absorbing the thermal deformation of the stiffening girder by the thermal deformation absorbing mechanism, it is possible to reliably prevent the occurrence of thermal stress in the stiffening girder. The other effects are the same as those of the third aspect.

According to the seventh aspect of the present invention, since the thermal deformation absorbing mechanism comprises an oil damper, the thermal deformation absorbing mechanism acts as a non-restraint for a time-dependent slow change such as a thermal deformation, and a restraint for a time-insensitive change. Can act as In addition, the same effect as any one of claims 4 to 6 can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall side view of a tower displacement suppressing type multi-span suspension bridge according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of a coupling mechanism of the multi-span suspension bridge of FIG. 1;

FIG. 3 is an enlarged view of a main part of a connecting means of the multi-span suspension bridge of FIG. 1;

FIG. 4 is an enlarged view of a main part of a structure for connecting a central portion of a main cable span to a stiffening girder.

FIG. 5 is an enlarged view of a main part of a structure for connecting a central portion of a main cable span to a stiffening girder.

FIG. 6 is an overall side view of a tower top displacement suppressing type multi-span suspension bridge according to a modified embodiment.

FIG. 7 is an enlarged view of a main part of a coupling mechanism of the multi-span suspension bridge of FIG. 6;

FIG. 8 is an overall side view of a tower-top displacement suppressing multi-span suspension bridge according to a modified embodiment.

FIG. 9 is an enlarged view of a main part of a coupling mechanism in a side tower of the multi-span suspension bridge in FIG. 8;

FIG. 10 is an overall side view of a tower top displacement suppressing type multi-span suspension bridge according to a modified embodiment.

11 is an enlarged view of a main part of a coupling mechanism of the multi-span suspension bridge in FIG. 10;

FIG. 12 is an overall side view of a conventional multi-span suspension bridge.

FIG. 13 is an enlarged view of a main part of the multi-span suspension bridge of FIG. 12;

Claims (7)

(57) [Claims] 1. A multi-span suspension bridge comprising at least one vertical intermediate tower erected between a pair of vertical side towers, wherein a top of the pair of side towers and an intermediate tower are connected to each other. A main cable connected to the anchorages at both ends of the suspension bridge, one continuous stiffening girder suspended from the main cable by a hanger and continuous to be able to transmit a load in the bridge axis direction, and continuous to the side tower and the intermediate tower A coupling mechanism for coupling the middle part of the stiffening girder, and a coupling means for coupling at least one end of the continuous stiffening girder to a corresponding anchorage, between the intermediate tower and the intermediate support between the side tower or the intermediate tower. ,
A multi-span suspension bridge that suppresses tower top displacement, wherein a central portion of a main cable span is connected to a continuous stiffening girder so that a load can be transmitted in a bridge axis direction. 2. A multi-span suspension bridge comprising at least one vertical intermediate tower erected between a pair of vertical side towers, wherein the top of the pair of side towers and the top of the intermediate tower are connected to each other. A main cable connected to the anchorages at both ends of the suspension bridge; a plurality of stiffening girders suspended from the main cable by hangers and connected so as to be able to transmit a load in the bridge axis direction; and an end of each stiffening girder. A coupling mechanism for coupling the corresponding side tower or intermediate tower, and coupling means for coupling at least one end of the plurality of stiffening girders to the corresponding anchorage, between the intermediate tower and the side tower or intermediate tower In the middle span,
A multi-span suspension bridge with suppressed tower top displacement, wherein a central portion of a main cable span is connected to a stiffening girder so that a load can be transmitted in a bridge axis direction. 3. A multi-span suspension bridge in which at least one vertical intermediate tower is erected between a pair of vertical side towers, wherein the top of the pair of side towers and the top of the intermediate tower are connected to each other. A main cable connected to the anchorages at both ends of the suspension bridge; a plurality of stiffening girders suspended from the main cable by hangers; and a corresponding side of an end of each stiffening girder disposed between the intermediate supports. Comprising a coupling mechanism coupled to the tower or the intermediate tower, between the intermediate tower and the intermediate tower between the side tower or the intermediate tower,
A multi-span suspension bridge with suppressed tower top displacement, wherein a central portion of a main cable span is connected to a stiffening girder so that a load can be transmitted in a bridge axis direction. 4. The tower according to claim 1, wherein a thermal deformation absorbing mechanism capable of absorbing thermal deformation is interposed between the continuous stiffening girder connected to the anchorage and the anchorage. Multi-span suspension bridge with suppressed top displacement. 5. The tower top displacement suppressing type multi span according to claim 2, wherein a thermal deformation absorbing mechanism is interposed between the stiffening girder connected to the anchorage and the anchorage. suspension bridge. 6. The multi-span suspension bridge of claim 3, wherein the coupling mechanism has a thermal deformation absorbing mechanism capable of absorbing thermal deformation. 7. The multi-span suspension bridge of claim 4, wherein the thermal deformation absorbing mechanism comprises an oil damper.