JP2014231721A - Bridge fall prevention device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bridge fall prevention device capable of reducing a size and weight in the whole device, and capable of also preventing the deterioration in a cable, and to also provide the bridge fall prevention device installable without impairing a landscape and design of a bridge.SOLUTION: The bridge fall prevention device is formed by mutually connecting two bridge structures including a bridge girder, and comprises a tubular member having one end side fixed to one bridge structure, having the other end side fixed to the other bridge structure and provided between the one bridge structure and the other bridge structure and a connection rope inserted into the tubular member and respectively provided with a stopper for locking on the tubular member in respective end parts, and the connection rope prevents the mutual respective bridge structures from moving in the separating direction via the tubular member.

Description

  The present invention relates to a technique for preventing a bridge girder from dropping due to shaking such as an earthquake by connecting two structures including the bridge girder, such as a bridge girder or a bridge girder and a pier, to each other.

As this type of prior art, for example, a falling bridge prevention device shown in Patent Document 1 below is known.
This falling bridge prevention device 100 includes a steel bracket 101 fixed to each end of adjacent bridge girders, and a connection cable 102 (hereinafter referred to as a cable) that is spanned between these brackets to connect the bridge girders. It comprises a deflection block 103 that prevents local bending of the cable 102 when the bridge girder is dropped, and a slack prevention device 104 such as a coil spring that prevents cable slack due to expansion and contraction of the bridge girder.

  That is, according to the falling bridge prevention device 100 having the above structure, adjacent bridge girders are connected to prevent a bridge girder whose end is placed on the upper part of a bridge pier or the like from falling. In addition, the bending block prevents local bending of the cable in order to cope with the fall of the bridge girder, and prevents the cable from being cut (shear failure) due to the concentration of shear stress. Further, the slack preventing device has a coil spring interposed between the bracket and the cable, and the slack of the cable is prevented by the tension of the coil spring.

JP 2003-138519 JP

  By the way, with the recent review of earthquake resistance in various structures, there is an increasing demand for a falling bridge prevention device having the above structure. In other words, the fall prevention device with the above structure can be improved in earthquake resistance with simple construction such as assembling cables and various devices to the bridge girder via brackets, so it is widely used regardless of whether it is a newly installed bridge or an existing bridge. It has been.

  However, the falling bridge preventing device having the above structure has a slack preventing device for preventing slack of the connecting cable and a deflection block for preventing local bending of the connecting cable on the same axis as the cable. The bracket in which is incorporated is very heavy and has to be long in the longitudinal direction of the bridge.

  Further, if attention is paid to the slack of the cable, since the recent bridge has a sophisticated design, the cable slacking irregularly does not necessarily give a desirable impression. Furthermore, there is room for improvement in the impression of the falling bridge prevention device itself having a large and rugged bracket, considering the design of the bridge.

  In addition, according to the above-described fallen bridge prevention device, since the cable for connecting the bridge girder and the abutment is directly exposed to sunlight, the polyethylene coating of the outer shell is easily deteriorated by ultraviolet rays, and depending on the degree of deterioration, the cable accompanying the intrusion of rainwater It leads to internal corrosion.

  The present invention has been made in view of such a technical background, and an object of the present invention is to provide a fall-bridge prevention device capable of reducing the size and weight of the entire device and preventing cable deterioration. Another object of the present invention is to provide a fall prevention device that can be installed without impairing the design of the landscape and the bridge.

In order to solve the above-described technical problem, the present invention is a falling bridge prevention device in which two bridge structures including a bridge girder are connected to each other,
A falling bridge prevention device that connects two bridge structures including a bridge girder to each other,
A tubular member having one end fixed to one bridge structure and the other end fixed to another bridge structure, and provided between the one bridge structure and the other bridge structure;
A connecting line that is inserted into the tubular member and provided with a stopper that is locked to the tubular member at each end;
With
The connecting rope is prevented from moving in a direction in which the bridge structures are separated from each other via the tubular member.

According to this invention comprised in this way, the connecting rope which connects two bridge structures containing a bridge girder mutually via a tubular member is provided. In addition, since the connecting rope is housed in the tubular member, it is possible to prevent the connecting rope from being deteriorated. Further, the tubular member can be expanded and contracted in a direction in which a bridge girder is bridged, and the stopper May regulate the extension range of the tubular member. That is, the tubular member may have a structure that expands and contracts following the movement of the bridge structure. In this way, it is possible to absorb the expansion and contraction of the bridge girder due to a temperature change or the like. Further, when the connected bridge girders are displaced in the vertical direction, local bending of the connecting rope can be mitigated by bending deformation of the tubular member. Therefore, concentration of shearing stress on the connecting line is avoided, and cutting (shear fracture) of the connecting line can be effectively prevented without using a deflection block. In addition, a connection cable slack prevention device is also unnecessary. Furthermore, the influence of ultraviolet rays on the connecting cord can be eliminated.

  The two bridge structures including the bridge girder described above are a combination of a so-called superstructure side structure composed of a bridge girder and a substructure side structure composed of an abutment, a pier, etc. The combination of these can be illustrated.

  Moreover, it is preferable that the tubular member is constituted by a multiple tube including an outer tube and an inner tube that is slidably inserted into the outer tube.

  According to this configuration, by making the tubular member a multi-pipe composed of an outer tube and an inner tube, it is possible to restore the expansion / contraction operation of the tubular member, that is, to perform repeated expansion / contraction operations of the tubular member. In addition, since the multiple tube structure is generally more resistant to buckling than the single tube structure, by adopting the multiple tube structure having such mechanical characteristics, while reducing the weight of the tubular member, The rigidity with respect to the local bending deformation of the tubular member is increased.

In addition, a bracket is provided on the bridge structure,
The connecting rope is preferably connected to the bridge structure via the bracket.

  In this configuration, when a bridge structure is connected using a connecting rope, the bridge structure is connected by providing a bracket. Further, as described above, in the present invention, a deflection bracket and a slack prevention device are not necessary, so a small bracket is sufficient. In other words, it is possible to reduce the size and weight of the entire device including the falling bridge prevention device and the bracket.

  The tubular member may be a steel pipe.

  The mechanical properties (strength, toughness, etc.) of the steel material used for the tubular member are appropriately determined in consideration of the diameter and thickness of the tubular member, the impact load when the bridge girder is dropped, and the like. For example, a steel material such as JIS SGP STK may be used.

  Further, the connecting rope may be a steel rope. That is, by using a steel lobe that is lightweight and has a high yield strength against a tensile load, the falling bridge prevention device can be further reduced in size and weight.

  As described above, according to the present invention, it is possible to provide a bridge-falling prevention device capable of reducing the size and weight of the entire device and preventing the deterioration of the cable. Moreover, the fall prevention device which can be installed without impairing the scenery and the design of the bridge can be provided.

The figure which shows the internal structure of the falling bridge prevention apparatus which concerns on this Embodiment. The figure which shows the installation state of the various sheath tubes which concern on this Embodiment. The figure which shows the internal structure of the protection pipe which concerns on this Embodiment. The figure which shows the protection pipe of the state which shrunk. The figure which shows the protection pipe of the state extended. The figure which shows the connection cable inserted in the protection pipe. The front view which shows a first-in type stop plate. The front view which shows a half-type stop plate. The figure which shows the positional relationship of the protection pipe of an extended state, and a connection cable. The figure which shows the deformation | transformation state of the protection pipe accompanying the fall of a bridge girder. The principal part enlarged view which shows the conventional fallen bridge prevention apparatus.

Hereinafter, an embodiment in which the falling bridge prevention device 1 according to the present invention is applied between an abutment and a bridge girder will be described.
In addition, although the installation structure of the falling bridge prevention device 1 shown in the present embodiment is slightly different on the abutment side and the bridge girder side, basically the same structure is provided on the abutment side and the bridge girder side. The same reference numerals are used for explanation. 1 to 6 and FIG. 9, the left hand of the drawing is the abutment side (lower work side), and the right hand of the drawing is the bridge girder side (upper work side).

  The falling bridge prevention device 1 shown in the present embodiment is provided between an abutment and a bridge girder, one end side is fixed to one bridge structure, and the other end side is fixed to another bridge structure. A protective pipe (tubular member) 2 provided between other bridge structures, and a connecting cable (through the protective pipe 2) and provided with stoppers 4 that are locked to the protective pipe at each end. The connecting cable 3 is prevented from moving in a direction in which the bridge structures are separated from each other via the protective pipe 2. The protective pipe 2 can be expanded and contracted in the direction in which the bridge girder is bridged, and the stopper 4 regulates the extension range of the protective pipe 2.

  As shown in FIG. 1, the protective pipe 2 includes a sheath tube 21 fixed on the abutment side (left hand side in FIG. 1), a sheath tube 22 fixed on the bridge beam side (right hand side in FIG. 1), and these sheath tubes 21. , 22 and an intermediate pipe 23 into which each end is slidably inserted. Further, a steel cap 24 that closes each end of the protective pipe 2 is provided at each end of the protective pipe 2.

  Each of the sheath pipes 21 and 22 is made of a steel pipe having the same diameter (JIS G 3452, JIS G 3444, etc.). Further, at the rear end of each of the sheath pipes 21 and 22, a bearing plate 25 that also serves as a flange for fixing the sheath pipe is provided, and each of the sheath pipes 21 and 22 is bolted to the abutment and the bridge girder via the buffer rubber 5, respectively. It is fastened.

  Moreover, the installation method of each sheath tube 21 and 22 in an abutment side and a bridge girder side is demonstrated with reference to FIG. 2, The sheath tube 21 of an abutment side is directly installed in the parapet (upright chest wall) P of an abutment. . Specifically, a sheath pipe insertion hole P1 penetrating in the longitudinal direction of the bridge is drilled in the parapet, and the sheath pipe 21 is incorporated and fixed in the bridge girder direction from the abutment side. In addition, the code | symbol P3 in FIG. 2 is a heart rebar.

Moreover, the sheath pipe 22 on the bridge girder side is assembled to the bridge girder via a steel bracket B. Specifically, a sheath pipe introduction hole B1 penetrating in the longitudinal direction of the bridge is formed in the bracket B in advance, and the sheath pipe 22 is incorporated and fixed in the abutment direction from the bridge girder side.
That is, the abutment-side sheath tube 21 and the bridge-girder-side sheath tube 22 are assembled so as to face each other with the bearing plate 25 as the back.
Moreover, the sheath pipe insertion hole P1 provided in the above-described abutment side parapet P and the sheath pipe insertion hole B1 provided in the bridge girder side bracket are formed on the same axis C, and are inserted into these various holes P1 and B1. The sheath tubes 21 and 22 are also located on the same axis. An intermediate pipe 23 is provided in the sheath tubes 21 and 22 installed in this way.

  The intermediate pipe 23 is sufficiently longer than the sheath tube 21 and the sheath tube 22 as shown in FIG. 3, and most of the intermediate pipe 23 is exposed to the outside with both ends inserted into the sheath tubes 21 and 22. . The intermediate pipe 23 is also made of a steel pipe (JIS G 3452, JIS G 3444, etc.) in the same manner as the sheath pipes 21, 22. Further, the outer diameter is slightly smaller than the inner diameter of the sheath pipes 21 and 22, and the intermediate pipe 23 can slide in the longitudinal direction of the bridge along the respective sheath pipes 21 and 22 arranged on the same axis. A sheet-like cushioning material is provided between the intermediate pipe 23 and each of the sheath tubes 21 and 22.

  The amount of insertion of the intermediate pipe 23 into each of the sheath pipes 21 and 22 will be described. In the sheath pipe 21 on the abutment side, the distance L1 from the open end 21a to the abutment side end portion 23a of the intermediate pipe is the sheath pipe diameter × 2 times. It is preferable that the amount of insertion is determined so as to be approximately. However, it may be more.

In the example shown in FIG. 3, the sheath pipe 22 on the bridge girder side is longer than the sheath pipe 21 on the abutment side, and the intermediate pipe 23 is inserted, and the expansion and contraction of the bridge extends in the depth direction inside the sheath pipe 22. A surplus length L3 corresponding to the amount is secured.
In the bridge girder side sheath tube 22, the distance L2 from the opening end 22a to the bridge girder side end portion 23b of the intermediate pipe varies depending on the amount of expansion / contraction of the bridge where the fall prevention device is installed, but usually L2 ≧ L3 + L1. The amount of insertion can be determined so that

In the present embodiment, the abutment-side sheath tube 21 and the intermediate pipe 23 are fixed by the bolts 26 in order to prevent the intermediate pipe 23 from being displaced unevenly between the sheath tubes 21 and 22.
That is, in the present embodiment, the protection pipe 2 can be expanded and contracted by sliding the intermediate pipe 23 with respect to the sheath pipe 22 on the bridge girder side. The sheath tube 22 corresponds to an outer tube, and the intermediate pipe 23 corresponds to an inner tube.

Next, the expansion and contraction operation of the protective pipe 2 following the change in the distance between the abutment and the bridge girder will be described.
When the bridge girder is thermally expanded as the temperature changes and the distance between the abutment and the bridge girder is reduced, the protective pipe 2 is shortened by the sliding of the intermediate pipe 23 with respect to the depth direction of the sheath pipe 22 (the direction of arrow S in FIG. 4) ( (See FIG. 4). Further, when the bridge girder contracts and the distance between the abutment and the bridge girder increases, the intermediate pipe 23 slides in the direction pulled out from the sheath tube 22 (in the direction of arrow G in FIG. 5), and the protective pipe 2 becomes longer (FIG. 5). reference).
Thus, the protection pipe 2 expands and contracts in the longitudinal direction of the bridge so as to follow the change in the distance between the abutment and the bridge girder, and absorbs the change in the distance.

Next, the connecting cable 3 inserted into the protective pipe 2 will be described.
The connecting cable 3 is made of, for example, a 7 × 7φ30 structural rope (strand galvanized specification), and its surface is covered with a polyethylene film having corrosion resistance.
In the present embodiment, two structural ropes are bundled together to be regarded as one connecting cable 3. The specifications of the connecting cable 3 are determined in consideration of the load resistance of the structural rope and the impact when the bridge girder is dropped.
Here, an example in which the connecting cable 3 is constituted by two structural ropes has been shown, but the connecting cable 3 can be formed by using one or more structural ropes.

  Further, the connecting cable 3 is sufficiently longer than the protective pipe 2, and each end 3a, 3b of the connecting cable is connected to the end 2a of the protective pipe with the connecting cable 3 inserted into the protective pipe 2 as shown in FIG. , 2b, respectively. Further, a steel sleeve 4 that also serves as a stopper is crimped and fixed to each end 3a, 3b of the connecting cable, and the connecting cable is provided by a stop plate 9 that is separately assembled to the bearing plate 25 of each sheath tube 21, 22. 3 is accommodated in the protective pipe 2 without coming out of the protective pipe 2.

Here, the stop plate 9 separately assembled to the sheath tubes 21 and 22 will be described.
As shown in FIGS. 7 and 8, the retaining plate 9 is a steel plate having a cable insertion hole 9c drilled in accordance with the cross-sectional shape of the connecting cable 3 using two structural ropes. In the embodiment, a first insertion type 9a (see FIG. 7) for fixing the connection cable 3 to the bearing plate after inserting the connection cable 3 into the cable insertion hole 9c, and a half type 9b for fixing to the bearing plate with the connection cable 3 sandwiched therebetween. Two types (see FIG. 8) are prepared. Further, the proper use is made according to the insertion direction of the connecting cable 3 with respect to the protective pipe 2.
In addition, the said cable penetration hole can be changed according to the number and cross-sectional shape of a structure rope.

  The positional relationship between the steel sleeve 4 and the stop plate 9 will be described with reference to FIG. 6. Between the steel sleeve 4 and the stop plate 9, a predetermined distance is provided on each end side of the connecting cable. L4 and L5 are secured. Specifically, half of the amount of expansion / contraction of the bridge girder (L3 in FIG. 3) at the end portions 3a and 3b of the connecting cable 3, that is, the lengths of L4 and L5 are set to L3 / 2, respectively. However, the lengths of these L4 and L5 may be different from each other as long as their total length is the same as L3.

  The relationship between the expansion and contraction operation of the protective pipe 2 and L4 and L5 will be described. The protective pipe 2 extends in the longitudinal direction of the bridge with the above interval (L4 + L5) as the upper limit as shown in FIG. At this time, L4 + L5 is set to be equal to the extension length L3 (FIG. 3) of the bridge girder. That is, the intermediate pipe 23 incorporated in the protective pipe 2 with the extension of the protective pipe 2 is drawn out from the sheath pipe 22 with L3, which is the sum of L4 + L5, as an upper limit value.

Here, the positional relationship between the intermediate pipe 23 and the sheath tube 22 will be described. As described above, the intermediate pipe 23 is pulled out from the sheath tube 22 with L3 as an upper limit value. It is initially set to have a length (L2) obtained by adding the above L3, that is, L4 + L5 to the diameter × 2 (L6). Therefore, even if the intermediate pipe 23 is pulled out from the sheath tube 22 due to the extension of the protective pipe 2, the rear end 23a of the intermediate pipe 23 remains in the sheath tube 22 as shown in FIG.
That is, even if the intermediate pipe 23 is pulled out from the inside of the sheath tube 22 due to the extension of the protective pipe 2, the intermediate pipe 23 does not fall out of the sheath tube 22, and the extra length of the sheath tube diameter × 2 (L6 in FIG. 9). The coupling state is maintained, leaving

Next, the steel cap 24 provided at each end 2a, 2b of the protective pipe 2 will be described.
The steel cap 24 closes the end portions 2a and 2b of the protective pipe in a state where the connecting cable 3 is inserted into the protective pipe 2 as shown in FIG. Further, in each steel cap 24, a cable retracting space 24a having a length of at least L3 / 2 is provided in the cap depth direction so as to avoid contact with each end portion of the connecting cable when the protective pipe is contracted. It has been. Further, the opening end of the steel cap 24 is provided with a flange 24b having substantially the same diameter as the bearing plate 25, and the steel cap 24 is fastened together with the bearing plate 25 to the abutment or the bridge girder by a bolt.

Next, the operation of the fallen bridge prevention device 1 during an earthquake will be described.
First, the operation in a situation where the distance between the abutment and the bridge girder has significantly increased due to the earthquake will be described.
In this situation, due to the relative movement of the abutment and the bridge girder, the abutment side sheath tube 21 and the bridge beam side sheath tube 22 move away from each other. Further, the stop plates 9 abut against the steel sleeves 4 of the connecting cable end portions 3a and 3b as the sheath tubes 21 and 22 move. This state can also be understood by referring to FIG. Further, when the stopper plate 9 abuts against the steel sleeve 4, the movement of the sheath tubes 21 and 22 with respect to the connecting cable 3 is prevented. At the same time, a drag force is generated in the connecting cable 3 to prevent the movement of the abutment-side sheath tube 21 and the bridge-girder-side sheath tube 22, and thereafter, the abutment and the abutment girder are provided with the bearing plate 25 provided in each of the sheath tubes 21, 22. The movement is prevented.

  If it is assumed that the bridge girder has fallen from the support due to an abutment earthquake collapse or the like, in such a situation, the protective pipe 2 is bent and droops due to the load acting on the connecting cable 3 (see FIG. 10). The local bending of the connecting cable 3 is prevented by the gentle bending. That is, the concentration of shear stress on the connection cable 3 is avoided by the deformation of the protective pipe 2, and the connection cable 3 is not cut (shear broken) by the shear stress and prevents the bridge girder from dropping.

  Thus, in the fallen bridge prevention device 1 shown in the present embodiment, the connecting cable 3 is housed in the protective pipe 2 constituted by the sheath pipes 21 and 22 and the intermediate pipe 23, so that the connecting cable is used without using a deflection block. 3 is prevented. Further, since the slack of the connecting cable 3 is not visible from the outside due to the protective pipe 2, it is not necessary to install a slack preventing device. In addition, since the deflection block and the slack prevention device are no longer required, the present fall bridge prevention device 1 can be greatly reduced in size and weight. Moreover, the size and weight reduction of the bracket B used at the time of installation of the fallen bridge prevention apparatus 1 can also be achieved.

  In addition, in the comparison of the bracket applied to the conventional fallen bridge prevention apparatus having the deflection block and the slack prevention apparatus and the bracket B applied to the fallen bridge prevention apparatus 1 shown in the present embodiment, the weight ratio is about 60%. It was possible to achieve weight reduction and downsizing of about 55% in terms of the dimensional ratio in the longitudinal direction of the bridge.

  Moreover, according to the falling bridge prevention apparatus 1 shown in this Embodiment, since the connection cable 3 is always stored in the protective pipe 2, the deterioration of the polyethylene film by ultraviolet rays can be suppressed over a long period of time.

  Thus, according to the falling bridge prevention device 1 shown in the present embodiment, the entire device can be reduced in size and weight, and the deterioration of the connection cable can be prevented at the same time. Moreover, since a simple and refined appearance can be exhibited by downsizing the apparatus and concealing the connecting cable, it is possible to install the fall prevention apparatus without impairing the scenery and the design of the bridge.

The embodiment described above is merely an example, and the structure of each part can be changed according to various specifications.
For example, in the above-described embodiment, the falling bridge prevention device is provided between the abutment and the bridge girder, but not only between the abutment and the bridge girder, but also between the bridge girder and the bridge girder, between the bridge girder and the pier, etc. Various examples are possible.

  Further, in this embodiment, the falling bridge prevention device 1 is provided directly on the abutment on the abutment side, but a bracket is also installed on the abutment side, and the abutment and the falling bridge prevention device 1 are connected via this bracket. May be.

Moreover, in this Embodiment, although the connection cable which consists of a structure rope is used, you may use a chain as a connection rope. In the present embodiment, a multi-pipe structure is adopted for the protective pipe 2. However, any single or multi-ply structure can be used as long as it is a tubular member that can expand and contract in the longitudinal direction of the bridge and does not cause local bending deformation when the bridge is dropped. . Further, a plurality of protective pipes 2 may be provided side by side corresponding to each structural rope. Moreover, in this Embodiment, although the intermediate pipe 23 is provided inside with respect to the sheath pipe, you may comprise separately the tubular member equivalent to a sheath pipe inside the intermediate pipe 23.
Thus, various things can be illustrated as a structure and installation method of the fallen bridge prevention apparatus 1 shown in this Embodiment.

1 Fall bridge prevention device 2 Protective pipe (tubular member)
2a Protection pipe abutment side end 2b Protection pipe bridge girder side end 3 Connection cable (connection cable)
3a Abutment side end 3b of the connecting cable 4b Bridge end 4 of the connecting cable 4 Steel sleeve (stopper)
5 Buffer rubber 9 Stop plate 21 Abutment side sheath pipe 21a Abutment side sheath pipe opening end 22 Bridge girder side sheath pipe 22a Abutment side sheath pipe opening end 23 Intermediate pipe 23a Intermediate pipe abutment side end 23b Intermediate pipe bridge girder Side end 25 Bearing plate (flange)
24 Steel cap 26 Bolt 100 Fall bridge prevention device 101 Steel bracket 102 Connecting cable 103 Deflection block 104 Slack prevention device B Bracket B1 Sheath tube introduction hole P Parapet P1 Sheath tube insertion hole

Claims (6)

A falling bridge prevention device that connects two bridge structures including a bridge girder to each other,
A tubular member having one end fixed to one bridge structure and the other end fixed to another bridge structure, and provided between the one bridge structure and the other bridge structure;
A connecting line that is inserted through the tubular member and provided with a stopper that is locked to the tubular member at each end;
With
The connection bridge prevents the bridge structure from moving in a direction in which the bridge structures are separated from each other via the tubular member.   The fallen bridge prevention device according to claim 1, wherein the tubular member can be expanded and contracted in a direction in which a bridge girder is bridged, and the stopper regulates an extension range of the tubular member.   The falling bridge prevention device according to claim 2, wherein the tubular member is a multiple tube including an outer tube and an inner tube slidably inserted into the outer tube. A bracket is provided on the bridge structure,
The falling bridge prevention device according to any one of claims 1 to 3, wherein the connecting rope is connected to a bridge structure through the bracket.   The fallen bridge prevention device according to any one of claims 1 to 4, wherein the tubular member is a steel pipe. 6. The falling bridge prevention device according to claim 1, wherein the connecting rope is a steel rope.

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