JP6227932B2 - Fall bridge prevention structure - Google Patents

Description

  The present invention relates to a fallen bridge prevention structure for preventing a fallen bridge.

  The bridge is composed of a lower structure such as an abutment and a pier and an upper structure such as a bridge girder. Further, the abutment, the pier and the bridge girder are not fixed, and the bridge girder is generally movable with respect to the abutment and the pier. For this reason, when an earthquake occurs, an inertial force due to three-dimensional positive and negative acceleration acts on the bridge girder via the abutment or pier, and when this inertial force is large, the bridge girder rotates, slides (horizontal direction), and rises. (Vertical direction) may be moved. And when the movement amount of the bridge girder becomes excessively large, the bridge girder may fall from the abutment or the pier. Especially in the case of a slanted bridge, if the bridge girder rotates in a direction toward the acute angle from the bridge axis, the bridge girder may be able to continue to rotate without being caught by the parapet part of the abutment, which is combined with sliding and lifting. As a result, the possibility of a fallen bridge becomes even greater.

  Therefore, conventionally, a technology for connecting the abutment or the pier and the bridge girder with a chain or the like (see Patent Document 1), or providing a protrusion on the lower surface of the bridge girder, the protrusion is caught on the pier or the abutment when the bridge girder slides or rotates. Technology (refer to Patent Document 2), a technology for providing a protrusion on the side of the bridge girder on the upper surface of the abutment or the pier, so that the bridge girder is hooked on the protrusion when the bridge girder is slid or rotated (Patent Document 3) (See below) and so on.

JP 2012-177255 A JP 2011-64000 A JP-A-9-195226

However, since the conventional techniques for preventing dropped bridges as described above allow the movement of the bridge girder within a certain range, fortunately, even if the bridge bridge is avoided, the bridge girder remains largely moved from the original position. There was a thing. In that case, a great deal of labor is required to return the bridge girder to the original position in the restoration work.
On the other hand, it is conceivable that the abutment or pier and the bridge girder are integrated by a rigid member, and the three-dimensional movement of the bridge girder is completely constrained, but in a large structure such as a bridge, the member and the member are combined. To integrate, it is assumed that large and heavy members are used in large quantities. However, there is often not enough space around the bridge girder, abutment, and piers to install the members, which makes it difficult to construct and requires a lot of time and cost to secure the space. There is a risk of losing.

  The present invention has been made in view of the above problems, and it is an object of the present invention to make it difficult for a bridge to be dropped in a bridge including an abutment, a pier, and a bridge girder, and to facilitate restoration work after an earthquake.

In order to solve the above-mentioned problems, the present invention provides a bridge drop bridge comprising a plurality of lower structures standing on the ground, and a bridge girder constructed between the lower structures and the lower structures. A first wire rod disposed between a first lower structure for supporting the bridge girder from one end side in the bridge axis direction and a first portion of the bridge girder on one end side in the width direction from the center. A second wire member disposed between the first portion and the second lower structure that supports the bridge girder from the other end side in the bridge axis direction, the second lower structure, and the bridge girder The fourth wire disposed between the third wire portion disposed between the second portion and the second portion on the other end side in the width direction from the center, the second portion, and the first lower structure. movement limiting wire having a wire section, a is, it can move in the axial direction on the lower structure and jig which is attached to at least one of the bridge girder With locked as being disposed substantially annular such a Suyo, and is characterized in that there is a tense state.

Here, the “substructure” refers to the abutment that supports the bridge girder at both ends of the bridge, or the pier that supports the bridge girder in the middle part of the bridge.
In addition, in the “substantially annular”, when both ends of the movement restricting wire are joined to each other, or when both ends are fixed together at the same part of the lower structure or the bridge girder, a plurality of movement restricting wires appear to be annular as a whole. And the like.
Further, the movement restriction wire may be fixed at a transit point such as the first structure, the second lower structure, or the first and second parts, or may be locked so as to be movable in the axial direction. Good.

In this way, when the bridge girder is about to move due to an earthquake, the movement limiting wire arranged at least partially in an annular shape and in a tensioned state restricts the movement of the bridge girder. At this time, since the movement restriction wire is deformed and the movement restriction wire slightly extends, the bridge girder is allowed to move to some extent, but when the seismic motion settles, the extension of the movement restriction wire returns. By trying to do so, the bridge girder is returned to the original position or a position slightly away from the original position. Thereby, it is not necessary to return the bridge girder to the original position, or even if it is necessary to return to the original position, the distance to move the bridge girder is shortened, so that the bridge can be restored easily and in a short time.
In addition, since it is only necessary to dispose a movement-restricting wire that is light and does not take a place, it is easy to secure a construction space and the construction can be easily performed. It can be applied not only to newly constructed bridges but also to existing bridges.
In addition, since the load exceeding the strength of the movement-restricted wire does not act on the lower structure, it can be prevented that even the lower structure is damaged due to the movement of the bridge girder, and the recovery becomes more difficult. .
Moreover, compared with the case where a hole or a groove is dug in the bridge girder or the lower structure, the movement-restricted wire can be easily passed over, and there is no fear of reducing the strength of the lower structure or the bridge girder.
In addition, unlike the case where the movement restriction wire is directly hung on the lower structure or the bridge girder, the movement restriction wire, the lower structure, or the bridge girder is less likely to be worn due to the movement of the bridge girder.

Desirably, in the above invention, at least one of the wire portions is inclined so as to be lowered toward the lower structure.
If it does in this way, since a movement restriction | limiting wire will come to pull a bridge girder also in the downward direction, the floating (movement to upper direction) of a bridge girder can be controlled.
Moreover, even if there is no part reaching the side of the bridge girder such as a parapet in the lower structure, the movement limiting wire can be easily bridged.

Desirably, in the above-mentioned invention, the movement limiting wire is an endless wire in which both ends are coupled.
If it does in this way, construction will become easy compared with the case where a movement restriction wire is fixed to a substructure or a bridge girder.

Preferably, in the above invention, the bridge girder is formed with a plurality of openings along the bridge axis direction, and the movement restriction wire is passed through each opening and wound around the bridge girder. It should be locked to a bridge girder.
In this way, it is possible to reduce the number of members used to transfer the movement restriction wire. Moreover, since a big frictional force arises between a movement restriction | limiting wire rod and a bridge girder, the force which controls the movement of a bridge girder can be raised.

  ADVANTAGE OF THE INVENTION According to this invention, in a bridge provided with an abutment, a bridge pier, and a bridge girder, it is hard to occur a fall bridge, and the restoration work after an earthquake can be made easy.

It is the figure which showed a part of bridge which has the fall-bridge prevention structure which concerns on 1st Embodiment of this invention, (a) is a side view, (b) is a top view. It is the longitudinal cross-sectional view which showed an example of the 2nd jig | tool which comprises the falling-bridge prevention structure of the embodiment from the bridge-axis direction. It is the figure which showed the structure in which the seismic reinforcement structure of FIG. 1 limits the movement of a bridge girder, and tries to return to the original. It is the figure which showed a part of bridge which has the fall-bridge prevention structure which concerns on the modification of the embodiment, (a) is a side view, (b) is a top view. It is the figure which showed a part of bridge which has the fall-bridge prevention structure which concerns on 2nd Embodiment of this invention, (a) is a side view, (b) is a top view.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

[Bridge fall prevention structure]
First, the fallen bridge prevention structure in this embodiment is demonstrated. 1A and 1B are a side view and a top view showing a central portion of a bridge having a fall-bridge prevention structure according to the present embodiment.
A bridge 10 according to the present embodiment includes an abutment (not shown) standing at both ends, a plurality of piers 1 erected at a predetermined interval between both abutments, an adjacent pier 1 between the abutment and the adjacent pier 1. And the bridge girder 2 etc. spanning between the bridge pier 1 and the like.

The pier 1 is made of reinforced concrete or steel. The width of the pier 1 is larger than the width of the bridge girder, and the upper surface thereof is a horizontal plane so that the bridge girder 2 can be placed thereon. A plurality of eaves 11 for supporting the bridge girder 2 are installed at predetermined locations on the upper surface. Hereinafter, if necessary, the bridge pier that supports the bridge girder 2 from one end side in the bridge axis direction (left side in FIG. 1) is referred to as a first pier 1A, and the pier that supports the bridge girder from the other end side in the bridge axis direction as a second pier 1B. write.
The bridge girder 2 is formed of reinforced concrete or steel. The shape of the bridge girder 2 as viewed from above shows a rectangular shape in which the bridge axis direction is longer than the width direction as an example in FIG. 1B, but the present invention is applicable to any shape, In some cases, the bridge axis direction is a rectangle shorter than the width direction, a square, a parallelogram, a trapezoid, or the like. The four corners of the lower surface of the bridge girder 2 are placed on the eaves 11. Hereinafter, if necessary, the part on the one end side in the width direction of the bridge girder 2 (the upper half in FIG. 1B) is the first part, and the part on the other side in the width direction (the lower half in FIG. 1B). This is referred to as the second part.
The bridge 10 is configured so that the bridge girder 2 does not fall from the pier 1 by the falling bridge prevention device 3. Although not shown, the bridge girder 2 constructed between the abutment supporting the end portion of the bridge 10 and the adjacent pier 1 is also prevented from falling by the same fall prevention device 3.

As shown in FIG. 1 (b), the falling bridge prevention device 3 is hung on the first jig 31 attached to the pier 1, the second jig 32 attached to the bridge girder 2, and the jigs 31 and 32. It is comprised with the transferred movement restriction | limiting wire (henceforth the wire 33).
The first jig 31 is attached to the upper surface of each pier 1 and on both sides in the width direction of the bridge girder 2 so as to protrude upward from the upper surface of the pier 1. For the first jig 31, for example, a post-construction anchor or the like is used when the pier 1 is a concrete structure, and a bolt or a rivet is used when the pier 1 is a steel structure. In addition, the first jig 31 is formed with a locking portion 31 a for locking the wire 33. The locking portion 31 a is, for example, a protrusion or groove formed in a substantially horizontal direction along the side surface of the first jig 31, and the first jig 31 is formed by placing the wire 33 in the protrusion or groove. It is to be locked to.

  Two second jigs 32 protrude laterally from the side surfaces at two positions on the both side surfaces along the long side of the bridge girder 2 at positions higher than the first jig 31 (the upper end portion in the present embodiment). It is attached to do. One of the two second jigs 32 attached to one surface is attached to one end side in the bridge axis direction from the center of the bridge girder 2, and the other is attached to the other end side in the bridge axis direction from the center of the bridge girder 2. It has been. Similar to the first jig 31, the second jig 32 has, for example, a post-construction anchor when the pier 1 is a concrete structure, and a pier 1 with a steel structure, for example, Use bolts, rivets, etc. A locking part 32 b for locking the wire 33 is formed at the tip of the second jig 32. The locking portion 32b is, for example, a ring or tube that opens in the longitudinal direction of the bridge girder 2, a hook whose tip is curved upward, and the like, and the wire 33 is passed through the ring or tube, or the hook By being hung, the second jig 32 is locked.

  In particular, when the upper part of the bridge girder 2 is a flange 24 extending in the width direction of the bridge girder 2 as shown in FIG. 2, a locking portion 32 b is formed at one end as the second jig 32. The other end portion is formed with a U-shaped engagement portion 32a opened on the opposite side to the bridge axis direction so that the flange 24 can be engaged with a portion extending in the bridge axis direction of the bridge girder 2. Use. Although details will be described later, when an earthquake occurs, the bridge girder 2 tends to move and a load in a direction to leave the bridge girder 2 may be applied to the wire rod 33. Will not come off.

  The wire 33 is a wire made of steel, carbon fiber, or synthetic fiber, and both ends are joined to form a ring. In addition, the joining method of the both ends of the wire 33 is arbitrary. Further, the wire rod 33 is hooked on the locking portions 31a and 32b of the first and second jigs 31 and 32, and is in a state of being tensioned to have a predetermined tension, whereby the first bridge pier 1A. 1st wire part 33a arrange | positioned between the 1st jig | tool 31 of this and the 2nd jig | tool 32 of the side surface (1st site | part of the width direction one end side rather than a bridge axis) of the width direction one end of the bridge girder 2. And a second jig 32 on the side surface at one end in the width direction of the bridge girder 2 and a second pier 1 (hereinafter referred to as a second pier 1B) that supports the bridge girder 2 from the other end in the bridge axis direction. A third wire portion 33c disposed between the wire portion 33b, the second pier 1B, and the second portion of the bridge girder 2 on the other side in the width direction from the bridge axis, the second portion, And a fourth wire portion 33d disposed between the pier 1A. The first to fourth wire portions 33a to 33d are disposed so as to be separated from the bridge beam 2 and inclined downward as approaching the first jig 31 from the second jig 32.

[Principle of fallen bridge prevention]
Next, a description will be given of a mechanism in which the above-mentioned fallen bridge prevention device 3 prevents the bridge girder 2 from dropping from the pier 1 due to an earthquake or the like. FIG. 3 is a diagram showing the bridge 10 from above when an earthquake occurs. In the figure, the solid line indicates the normal state, and the double chain line indicates the vibration state.

  For example, when an earthquake motion acts on the bridge 10 and an inertial force that rotates on the bridge girder 2 acts as shown in FIG. 3, one end side in the bridge axis direction of the second jig 32 attached to the bridge girder 2 and A second jig 32 on one end side in the width direction (upper left in the figure) and a second jig 32 on the other end side in the bridge axis direction and on the other end side in the width direction (lower right side in the figure) are arranged in an annular shape. A certain wire 33 is pulled to change the arrangement shape of the wire 33. However, since the wire rod 33 is in a tensioned state, the first and second jigs 31 and 32 regulate the deformation of the wire rod 33 by the frictional force acting between the wire rod 33 and the rotation of the bridge girder 2 is Limited by the wire 33. On the other hand, since the wire rod 33 is extended by the action of a load, the bridge girder 2 is allowed to move by a slight distance that does not drop. However, when the seismic motion is settled, the bridge girder 2 returns to the original position or close to the original position by the force that the elongation of the wire rod 33 returns.

Although illustration is omitted, when an inertial force is applied to the bridge 10 so as to slide in the direction of the bridge girder 2, the second jig 32 attached to the bridge girder 2 is opposite to the sliding direction. The two second jigs 32 on the side pull the wire 33 and try to change the arrangement shape of the wire 33, but the rotation of the bridge girder 2 is performed by the wire 33 in the same manner as in the rotation. Limited. When the seismic motion settles, the bridge girder 2 returns to the original position or close to the original position.
Further, when an earthquake force acts on the bridge 10 and an inertial force that floats on the bridge girder 2 acts, the first to fourth wire portions 33a that incline downward as the second jig 32 approaches the first jig 31. The lifting of the bridge girder 2 is limited by the tension of ~ 33d.

  As described above, the bridge 10 of the present embodiment includes the first pier 1A (lower structure) that supports the bridge girder 2 from one end side in the bridge axis direction, and the first of the bridge girder 2 on the one end side in the width direction from the center. Arranged between the first wire portion 33a disposed between the portion 2a, the first portion 2a, and the second pier 1B (lower structure) that supports the bridge girder 2 from the other end side in the bridge axis direction. The second wire portion 33b, the second bridge pier 1B, the third wire portion 33c disposed between the bridge beam 2 and the second portion 2b on the other side in the width direction from the center, and the second portion 2b and a fourth wire rod portion 33d disposed between the first pier 1A, and at least a portion of the wire rod 33 is substantially annular and is disposed in a tensioned state. Yes.

For this reason, when the bridge girder 2 is about to move due to an earthquake, the wire rod 33 arranged at least partially in an annular shape and in a tensioned state restricts the movement of the bridge girder 2. At this time, since the arrangement shape of the wire rod 33 is deformed and the wire rod 33 extends slightly, the bridge girder 2 is allowed to move to some extent. However, when the seismic motion settles, the wire rod 33 tends to return to stretch. As a result, the bridge girder 2 is returned to the original position or a position slightly away from the original position. This eliminates the need to return the bridge girder 2 to the original position, or even if it is necessary to return to the original position, the distance to move the bridge girder 2 is shortened, so that the bridge 10 can be restored easily and in a short time. it can.
Moreover, since it is only necessary to arrange the light wire 33 that does not take up a place, it is easy to secure a construction space and the construction can be easily performed. It can be applied not only to newly constructed bridges but also to existing bridges.
Moreover, since the load exceeding the strength of the wire rod 33 does not act on the bridge pier 1, it is possible to prevent the bridge pier 1 from being damaged by the movement of the bridge girder 2 and making recovery difficult.

Moreover, in this embodiment, the 1st-4th wire part 33a-33d inclines so that it may go down toward a lower structure.
By doing so, the wire rod 33 pulls the bridge girder 2 in the downward direction, so that it is possible to restrict the floating (upward movement) of the bridge girder 2.
Further, unlike the abutment, even if the pier 1 does not have a part reaching the side of the bridge girder like a parapet, the wire 33 can be easily bridged.

Moreover, in this embodiment, the wire 33 is an endless wire that joins both ends.
By carrying out like this, compared with the case where the wire 33 is fixed to the pier 1 or the bridge girder 2, construction becomes easy.

In the present embodiment, the first and second jigs 31 and 32 for locking the wire 33 are attached to the pier 1 and the bridge girder 2.
By carrying out like this, compared with the case where a hole or a groove is dug in the bridge girder 2 or the pier 1, the wire 33 can be easily passed over, and there is no fear of reducing the strength of the pier 1 or the bridge girder 2.
Further, unlike the case where the wire rod 33 is directly hung on the pier 1 or the bridge girder 2, the wire rod 33, the pier 1 and the bridge girder 2 are not easily worn by the movement of the bridge girder 2.

<Modification of First Embodiment>
Next, a modification of the above embodiment will be described.
Here, only differences from the above embodiment will be described, and description of common points will be omitted.

4A and 4B are a side view and a top view of the bridge 10A having the fallen bridge prevention structure of the present modification.
As shown in FIG. 4, the bridge 10 </ b> A of the present modification is different from the above-described embodiment in the configuration of the falling-bridge preventing instrument.
Specifically, as shown in FIG. 4A, in the fallen bridge prevention device 3A of the present modification, the first jig 31 is provided on the side surfaces of the bridge pier 1 facing each other, and the second jig 32 is the bridge girder 2B. It is provided at the lower end of the side surface along the long side. In addition, when the flange extended in the width direction of the bridge girder 2 is formed in the lower part of the bridge girder 2, this deformation | transformation is carried out by rotating the 2nd jig | tool 32 shown in FIG. 2 upside down. It can also be used in examples. By arranging the jigs 31 and 32 in this way, the arrangement shape of the wire 33 to be bridged also changes, but when an earthquake occurs, it functions in the same manner as the fallen bridge prevention device 3 of the above embodiment.

As described above, in the present modification, the first jig 31 is attached to the opposite side surfaces of the first and second piers 1A and 1B.
By doing so, it is possible to obtain the same bridge prevention effect as that of the bridge 10 of the above embodiment, and it is possible to perform the construction even when it is difficult to attach the first jig 31 to the upper surface of the pier 1. Become.
Moreover, when the 1st jig | tool 31 is provided in the upper surface of a bridge pier like the above-mentioned embodiment, when each bridge girder of a bridge which has a some bridge girder is made into a fall-bridge prevention structure, the wire 33 bridge | crossed over a certain bridge girder And the wire rod 33 bridged over the adjacent bridge girder are locked so as to intersect with the first jig, and the wire rod 33 and the wire rod 33 interfere with each other to make the arrangement difficult. In the event of an earthquake, there is a risk that the wire rod 33 and the wire rod 33 will be rubbed and damaged. However, according to this modification, even if there are a plurality of bridge girders, the first jig is provided for each bridge girder. Therefore, there is no worry of damage due to interference or friction between wires.

Second Embodiment
Next, a second embodiment of the present invention will be described.
Here, only differences from the first embodiment will be described, and description of common points will be omitted.

[Falling bridge prevention structure]
FIG. 5 is a side view and a top view of a bridge having a fall-bridge prevention structure according to the present embodiment.
As shown in FIG. 5, the bridge 10 </ b> B of the present embodiment is different from the first embodiment in the structure of the bridge girder and the configuration of the falling-bridge preventing instrument.

Specifically, the bridge girder 2A of the present embodiment includes a plurality of steel frames 22, a plurality of sleepers 23, and the like.
Each steel frame 22 spans between adjacent piers 1 and piers 1 so as to be parallel to each other.
The sleepers 23 are arranged at predetermined intervals so as to straddle the two steel frames 22.
Then, by arranging the steel frame 22 and the sleepers 23 in this way, a plurality of openings 2Aa are formed in the bridge beam 2A.
Moreover, the fallen bridge prevention instrument 3B of the present embodiment does not include the second jig 32, and the wire 33 is passed through each opening 2Aa and is wound around the steel frame 22. That is, in this embodiment, the steel frame 22 plays the same role as the second jig.

As described above, in the present embodiment, a plurality of openings 2Aa are formed in the bridge girder 2A along the bridge axis direction, and the wire rod 33 is passed through each opening 2Aa and wound around the bridge girder 2A. 2A.
By doing so, it is possible to obtain the same bridge prevention effect as that of the bridges 10 and 10A of the first embodiment, and it is possible to reduce the number of members used for the wire 33.
Moreover, since a big frictional force arises between the wire rod 33 and the bridge girder 2, the force which controls the movement of the bridge girder 2 can be raised.

As mentioned above, although this invention was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.
For example, in the above-described embodiment, only one wire rod that is an endless wire is used for one bridge girder, but a plurality of wire rods may be used.
Moreover, in the said embodiment, although the wire was arrange | positioned so that it might become one big cyclic | annular form, you may make it have two cyclic | annular parts, for example, arrange | position a wire in the shape of 8 character.

Moreover, in the said embodiment, although the wire was passed over the abutment and the bridge girder using the jig | tool, a hole and a groove | channel may be directly formed in an abutment and a bridge girder, and you may make it let a wire pass through the hole or a groove | channel.
Moreover, in the said embodiment, although the 2nd jig | tool was attached to the side surface of a bridge girder, the 2nd jig | tool which should be attached to the width direction one end side can be attached to the arbitrary locations of a 1st site | part, and the width direction other end The second jig to be attached to the side can be attached to any part of the second part.
In the above embodiment, the first jig is attached to the upper surface of the abutment or the side surface facing each other, and the second jig is attached to the side surface of the abutment. However, the first jig is attached to the side surface facing the width direction of the abutment. You may make it attach or attach a 2nd jig | tool to the upper surface or lower surface of a bridge girder.
Moreover, in the said embodiment, although the 2nd 1st jig | tool was attached to each pier, it is good also as one each.

10, 10A, 10B Bridge 1 Pier (substructure)
2, 2A, 2B Bridge girder 2Aa Opening 2a First part 2b Second part 31 First jig 32 Second jig 33 Wire 33a First wire part 33b Second wire part 33c Third wire part 33d Fourth wire part a Bridge axis

Claims (4)

A bridge fall prevention structure for a bridge comprising a plurality of lower structures erected on the ground, and a bridge girder constructed between the lower structure and the lower structure,
A first wire member disposed between a first lower structure that supports the bridge girder from one end side in the bridge axis direction and a first portion of the bridge girder on one end side in the width direction from the center;
A second wire portion disposed between the first portion and the second lower structure that supports the bridge girder from the other end side in the bridge axis direction;
A third wire portion disposed between the second lower structure and the second portion of the bridge beam on the other end side in the width direction from the center;
A movement limiting wire having the fourth part disposed between the second part and the first lower structure,
Together are so engaged as to be axially movable in a jig which is attached to at least one of the lower structure and the bridge girder, it is arranged in a substantially circular such the Suyo and a tense state A structure that prevents falling bridges.   The fallen bridge prevention structure according to claim 1, wherein at least one of the wire portions is inclined so as to descend toward the lower structure.   The falling bridge prevention structure according to claim 1 or 2, wherein the movement restricting wire is an endless wire in which both ends are joined. A plurality of openings are formed in the bridge girder along the bridge axis direction,
The fall-prevention bridge according to any one of claims 1 to 3, wherein the movement restriction wire is passed through each opening and is locked to the bridge girder by being wound around the bridge girder. Construction.

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