JP4448956B2 - Shock absorber and falling bridge prevention device incorporating the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shock absorber and a fallen bridge prevention device incorporating the shock absorber, and more specifically, for example, a shock absorber that is installed in a parapet of an abutment and is used to reduce impact and absorb energy when a bridge girder collides. The present invention also relates to a fallen bridge prevention device incorporating the function.
[0002]
[Prior art]
In general, a gap is formed between the parapet of the abutment and the end portion of the bridge girder in order to allow expansion / contraction due to temperature change of the bridge girder and rotational displacement of the bridge girder due to live load. In recent years, rubber bearings are often used as bearings for supporting the vertical load of bridge girders. This rubber bearing is sheared during an earthquake and resists horizontal force with the force of its spring, but when a large horizontal force exceeding this is applied, the bridge girder collides with the parapet, so this impact force is weakened. A shock absorber is installed on the parapet side.
[0003]
Various types of shock absorbers have been proposed in the past, such as those made simply of rubber and those made of a honeycomb-like buffer material. However, these have advantages and disadvantages. In the case of rubber, the amount of energy absorption is very small, and in the case of the honeycomb-shaped cushioning material, the amount of energy absorption is large, but when a specific load is reached, the supporting force for loads beyond that is lost.
[0004]
[Problems to be solved by the invention]
The present invention has been made based on the technical background as described above, and achieves the following object.
An object of the present invention is to provide a shock absorber capable of expecting a large amount of energy absorption with a simple structure and a fallen bridge prevention device incorporating the shock absorber.
[0005]
[Means for Solving the Problems]
The present invention employs the following means in order to achieve the above object.
That is, the present invention is a shock absorber provided in one structure, for mitigating the impact force received from the other structure, and for absorbing energy,
A support tube fixed to the one structure;
A support plate fixed to the end of the support cylinder and having a tapered hole in the center;
The shock absorber includes a hollow cylindrical wedge having a tip end fitted into the tapered hole.
[0006]
The present invention is also a shock absorber provided in one structure for relaxing the impact force transmitted from the other structure and absorbing energy,
A support tube fixed to the one structure;
A bearing plate that is movably disposed in the axial direction inside the support cylinder and has a tapered hole in the center;
A hollow cylindrical wedge whose tip is fitted into the tapered hole;
The shock absorber includes an annular elastic body disposed inside the support cylinder defined by the pressure plate.
[0007]
Furthermore, the present invention is a falling bridge prevention device for preventing the bridge girder from dropping from a lower structure such as a bridge pier or an abutment by a connecting member having one end attached to the bridge axial direction end of the bridge girder. There,
A support tube fixed to the end of the bridge beam;
A bearing plate that is movably disposed in the axial direction inside the support cylinder and has a tapered hole in the center;
A hollow cylindrical wedge in which a tip portion is fitted into the tapered hole and the connecting member is inserted;
There is a falling bridge prevention device including an annular elastic body that is disposed inside the support cylinder defined by the bearing plate and through which the connecting member is inserted.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an application example of a shock absorber 1 according to the present invention. The bridge girder 2 is supported at a vertical load by a rubber support 4 installed on the abutment 3 at the end of the girder. As is well known, the rubber support 4 is formed by laminating a rubber layer and a steel plate. A gap 6 is formed between the girder end of the bridge girder and the parapet 5 of the abutment 3, and the shock absorber 1 is installed in this gap 6 and fixed to the parapet 5 so as to face the girder end.
[0009]
2 is an axial cross-sectional view showing details of the shock absorber 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG. The shock absorber 1 includes a support cylinder 7, a bearing plate 8, and a cylindrical wedge 9. One end of the support cylinder 7 is fixed to the base plate 10 by welding or the like, and the base plate 10 is fixed to the parapet 5 by anchor bolts 11.
[0010]
The bearing plate 8 is fixed to the other end of the support cylinder 7 by welding or the like, and a tapered hole 12 whose diameter gradually decreases toward the support cylinder 7 is formed in the center of the bearing plate 8. A front end portion of a cylindrical wedge 9 having a stopper portion 16 at the rear end portion is fitted into the tapered hole 12. The outer peripheral surface of the cylindrical wedge 9 is a tapered surface 9 a whose diameter gradually decreases in the same direction as the tapered hole 12, and is fitted into the tapered hole 12 while being lightly press-fitted when attached to the pressure bearing plate 8. The taper angle of the taper hole 12 and the outer peripheral surface 9a of the cylindrical wedge 9 is selected from the range of 1 to 15 degrees. Each member constituting the shock absorber 1 including the bearing plate 8 and the cylindrical wedge 9 is made of steel.
[0011]
In the shock absorber 1, when an impact load P is applied due to the inertial force acting on the bridge girder 2 in the event of a large earthquake, the cylindrical wedge 9 is pressed into the tapered hole 12 while being squeezed in the radial direction, as shown by the chain line in FIG. It is pushed into the support cylinder 7. At this time, for example, when the nail is driven into the wood with a hammer, the cylindrical wedge 9 is such that the inertial force of the hammer is absorbed by the frictional force between the nail and the wood and the reaction is eliminated (that is, the energy of the hammer is absorbed). The energy due to the inertial force of the bridge girder 2 is absorbed by the frictional force generated between the support plate 8 and the bearing plate 8.
[0012]
In addition, when a nail is driven into wood with a hammer, the nail enters the wood with a small force at first, but as the force increases gradually as the nail enters, the cylindrical wedge 9 has a bearing plate in accordance with the squeezing press-fitting. The frictional force with 8 increases sequentially. As described above, since the frictional force sequentially increases with the press-fitting, a high energy absorption effect can be obtained.
[0013]
FIG. 4 is an axial sectional view showing another embodiment, and FIG. 5 is a view taken along the line BB in FIG. In the above embodiment, one cylindrical wedge 9 is attached to the bearing plate 8, but a plurality of cylindrical wedges 9 may be attached to the bearing plate 8 as in this embodiment.
6 is an axial cross-sectional view showing still another embodiment, and FIG. 7 is a cross-sectional view taken along the line CC of FIG. In this embodiment, the bearing plate 8 is disposed inside the support cylinder 7 so as to be movable in the axial direction. Further, a lid body 13 and a stopper plate 14 are provided at the front end and the rear end of the cylindrical wedge 9, respectively, and these members 13 and 14 are integrally connected by a bolt 15. The outer peripheral surface of the lid 13 at the tip is a tapered surface that is larger than the taper angle of the cylindrical wedge 9.
[0015]
An annular rubber 20 is disposed in contact with the inner surface of the support plate 8 inside the support cylinder 7 defined by the support plate 8. The annular rubber 20 is made of natural rubber, chloroprene rubber, or the like, and has an inner peripheral tapered surface 20a and an outer peripheral tapered surface 20b whose diameter gradually decreases toward the bearing plate 8 on the inner and outer periphery. In the figure, reference numeral 22 denotes a reinforcing rib.
[0016]
In the case of this embodiment, when the cylindrical wedge 9 receives an impact load P, the bearing plate 8 moves, and the annular rubber 20 is compressed and deformed while bulging in the radial direction, so that the impact is reduced and energy is absorbed. When a predetermined load is reached, the cylindrical wedge 9 is press-fitted into the tapered hole 12, and energy is absorbed by friction.
[0017]
Since the annular rubber 20 has an outer peripheral tapered surface 20b that forms a gap 21 with the support cylinder 7, it can bulge outward as well as radially inward. Therefore, the deformation amount of the annular rubber 20 is large, and a high energy absorption effect is obtained. Further, since the annular rubber 20 also has a tapered surface 20a on the inner periphery, even if it bulges inward in the radial direction, it does not block the press-fitting of the cylindrical wedge 9, and is a cylindrical shape pushed out from the bearing plate 8. The wedge 9 enters while pushing away the inner peripheral surface of the annular rubber 20.
[0018]
When the annular rubber 20 is used together as in this embodiment, the cylindrical wedge 9 begins to be press-fitted when the load received from the bridge girder 2 reaches about 20% to 60% of the design load. Design so that fixed press-fit is completed. In addition, as in the embodiment shown in FIGS. 2 and 3, when rubber is not used together, press-fitting starts from about 0 to 10% of the design load.
[0019]
8 and FIG. 9 show an embodiment of the falling bridge prevention device incorporating the shock absorber shown in FIG. 6 and FIG. 7, FIG. 8 is a front view seen along the direction perpendicular to the bridge axis, and FIG. 9 is a horizontal sectional view. It is. This embodiment is an example in which the end portions of the bridge girders 2 and 2 are connected by the falling bridge prevention device 30.
[0020]
The falling bridge prevention device 30 is attached to the end portions of the bridge girders 2 and 2 and has a connecting cable 31 that is a member for connecting these end portions of the girders. As shown in FIG. 9, the falling bridge prevention device 30 is attached to the end of the girder via a bracket 32. The bracket 32 includes a mounting plate 35 fixed to the web of the bridge girder 2 (in the case of a steel girder) by a number of mounting bolts 34 via a liner plate 33, and a pair of upper and lower horizontal plates 36, 36 provided on the mounting plate 35. And a vertical plate 37 perpendicular to the bridge axis direction crossing the intermediate portion of these horizontal plates 36, 36, and a pair of partition plates 38, 38 provided between the horizontal plates 36, 36.
[0021]
The support cylinder 7 constituting the shock absorber 1 is fixed horizontally to the vertical plate 37 via the base plate 10. As described in the above embodiment, the support cylinder 8 and the annular rubber 20 are arranged inside the support cylinder 7, and the cylindrical wedge 9 is fitted in the tapered hole 12 of the support cylinder 8.
[0022]
A deflection block 40 is fixed to an entrance of a space 39 defined by the horizontal plate 36 and the partition plates 38 and 38. The deflection block 40 is composed of two divided blocks formed of a synthetic resin such as polyethylene, and has an insertion hole 41 for a connecting cable that gradually widens on the inlet side.
[0023]
The connecting cable 31 is inserted through the deflection block 40, the vertical plate 37, the annular rubber 20 and the cylindrical wedge 9, and the end 42 projects from the cylindrical wedge 9. The connecting cable 31 includes a PC steel strand 31a, a steel apartment 31b into which the PC steel strand 31a is inserted and fixed, and a synthetic resin covering material 31c that covers the PC steel strand 31a. Yes.
[0024]
A male screw portion 43 is formed at the end portion 42 of the connecting cable 31, that is, the end portion 42 of the apartment 31b. The male screw portion 43 is provided with a washer 44 and a nut 45 that constitute a stopper. A coil spring 46 surrounding the apartment 31b is disposed between the washer 44 and the bearing plate 8. The amount of movement of the connecting cable 31 can be adjusted by changing the mounting position of the nut 45. The cylindrical cover 47 is for covering the end 42 of the connecting cable 31 and is detachably attached to the support cylinder 7.
[0025]
When the bridge girder 2 receives an inertial force due to a large earthquake in the above-described fallen bridge prevention device, a horizontal impact force P acts on the connecting cable 31. Due to this impact force, the coil spring 46 is compressed and deformed, and the bearing plate 8 moves in the support cylinder 7. By the movement of the pressure bearing plate 8, the annular rubber 20 is compressed and deformed while bulging in the radial direction as described in the above embodiment. Further, the cylindrical wedge 9 is press-fitted into the tapered hole 12 of the bearing plate 8, and impact energy is absorbed by the compression deformation of the annular rubber 20 and the friction during the press-fitting of the cylindrical wedge 9.
[0026]
FIG. 10 is a load-displacement diagram (P-δ diagram) showing the mechanical characteristics of the shock absorber according to the present invention. A is a characteristic line when only rubber is used, B is a characteristic line when only a cylindrical wedge is used, and C is a characteristic line when rubber and a cylindrical wedge are used together. The hatched portions X ₁ and X ₂ indicate energy absorption amounts when only rubber is used and when rubber and a cylindrical wedge are used in combination, respectively. When only rubber is used, the rise is large and the buffering action is excellent, but the energy absorption is small. On the other hand, when the wedge is used, the amount of deformation until reaching the design load P is large, so that the amount of energy absorption increases. Therefore, when used together these rubbers and wedges (characteristic line C), serves a predetermined load P ₁ Dekusabi, good characteristics are obtained for cushioning and energy absorption amount.
[0027]
The above embodiment is merely an example, and the present invention can be modified in various ways. That is, the shock absorber according to the present invention is not limited to the above embodiment, and can be applied to various structures as long as it is a structure on which an impact load acts. Moreover, the shape of each member which comprises a buffer device is not restricted to the said embodiment, A required effect is acquired even if it replaces with a cylindrical shape and is a polygonal cylinder.
[0028]
【The invention's effect】
As described above, the shock absorber according to the present invention is designed to absorb energy by friction during the press-fitting of the wedge, and can obtain a large amount of energy absorption with a simple structure.
[Brief description of the drawings]
FIG. 1 is a diagram showing an application example of a shock absorber according to the present invention.
FIG. 2 is an axial sectional view showing details of the shock absorber.
FIG. 3 is a cross-sectional view taken along line AA in FIG.
FIG. 4 is an axial cross-sectional view showing another embodiment.
FIG. 5 is a view taken along the line BB in FIG. 4;
FIG. 6 is an axial sectional view showing still another embodiment.
7 is a cross-sectional view taken along line CC in FIG.
FIG. 8 is a view taken along a direction perpendicular to the bridge axis, showing an embodiment of a falling-bridge preventing device incorporating the shock absorber shown in FIGS. 6 and 7;
FIG. 9 is a horizontal sectional view of the above.
FIG. 10 is a dynamic characteristic diagram of the shock absorber according to the present invention.
[Explanation of symbols]
1: shock absorber 2: bridge girder 3: abutment 4: rubber bearing 8: bearing plate 9: cylindrical wedge 12: taper hole 20: annular rubber 30: falling bridge prevention device 31: connecting cable 32: bracket 44: washer 45: nut 46 :coil spring

Claims (3)

A shock absorber that is provided in one structure, reduces the impact force received from the other structure, and absorbs energy,
A support tube fixed to the one structure;
A support plate fixed to the end of the support cylinder and having a tapered hole in the center;
A shock absorber comprising a hollow cylindrical wedge having a tip end fitted in the tapered hole. A shock absorber provided in one structure for relaxing the impact force transmitted from the other structure and absorbing energy,
A support tube fixed to the one structure;
A bearing plate that is movably disposed in the axial direction inside the support cylinder and has a tapered hole in the center;
A hollow cylindrical wedge having a tip fitted in the tapered hole;
A shock absorber comprising: an annular elastic body disposed inside the support cylinder defined by the pressure bearing plate. A bridge prevention device for preventing the bridge girder from falling from a lower structure such as a bridge pier or an abutment by a connecting member having one end attached to the bridge axial direction end of the bridge girder,
A support tube fixed to the end of the bridge beam;
A bearing plate that is movably disposed in the axial direction inside the support cylinder and has a tapered hole in the center;
A hollow cylindrical wedge in which a tip portion is fitted into the tapered hole and the connecting member is inserted;
A falling bridge prevention device comprising: an annular elastic body that is disposed inside the support cylinder defined by the bearing plate and through which the connecting member is inserted.

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