JP2746834B2 - Bridge body damping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bridge body vibration damping device for suppressing the vibration of a bridge body generated during an earthquake or the like.

[0002]

2. Description of the Related Art In recent years, long bridges have been constructed. However, in long bridges, the response in the bridge axis direction caused by a low-order vibration mode in the bridge axis direction becomes large. Is desired. In a long bridge, the low-order vibration mode has a long cycle and is difficult to control due to low acceleration and large displacement.

Conventionally, for damping a bridge during an earthquake, dampers as shown in FIGS. 4 to 6 are provided at both ends of the bridge or at the main tower. FIG. 4 shows a seismic isolation device 30 in which a lead 33 and a piston 35 are accommodated in a cylinder 31 provided with an orifice 32 and sealed with a sealing material 34. When the piston 35 moves in the direction indicated by the arrow 36, lead acts as an energy absorbing material. In the seismic isolation device 40 of FIG. 5, a laminated rubber 43 is interposed between an upper plate 41 and a lower plate 42, and a lead plug 44 is erected at the center. There is a seismic isolation effect in both directions of the arrows 45 and 46. FIG. 6 shows a seismic isolation device using the bending of a bar 53, which is a mild steel bending beam. Install it. When the relative motion indicated by the arrow 55 occurs due to the earthquake,
The bar 53 bends as shown by the flexure range 54 and seismically isolates. Each of these devices has a small amount of displacement for a large displacement, and requires the installation of a large number of devices.
It will be expensive.

[0004] Large bridges require large dampers. However, a long bridge has a problem that the natural cycle is long and the response displacement is very large, so that the effect of the damper is insufficient.Moreover, since a large braking force is required intensively,
It is difficult and expensive to design.

[0005]

SUMMARY OF THE INVENTION In a long bridge,
Conventionally, there is a risk of a bridge being dropped due to a large displacement during an earthquake, and therefore a large damper must be provided.
When displacement could not be absorbed, there were significant restrictions on the bridge design. An object of the present invention is to provide a structure in which a sliding body is provided on a bridge and the damping effect of its frictional resistance is used to prevent earthquake damage in order to minimize damage to a long bridge during an earthquake. And

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has a sliding surface which is relatively movable along a bridge to be damped and which is in contact with the bridge. A vibration damping device for a bridge body, which extends axially outward of a bridge body, and the extended portion comprises a vibration damping element fixed to an abutment and / or ground.

Further, another invention of the present invention relates to a damping element which is fixed to a bridge to be damped, extends outward in the bridge axis direction, and the outer portion of the bridge comes into contact with the ground on a sliding surface. The present invention provides a bridge body vibration damping device.

[0008]

The vibration damping device according to the present invention extends continuously on both sides of the bridge shaft and is constructed continuously and integrally. In the first aspect of the present invention, the vibration damping device has a bridge body and an edge cut so that mutual displacement can be caused, and vibration is attenuated by mutual friction. In this structure, the braking force for braking the displacement due to the earthquake is distributed over the entire bridge surface. Further, since a tensile force due to frictional force is generated in this vibration damping device, a design corresponding to this structure is taken into consideration.

[0009] In the second invention, the vibration damping device is integrated with the bridge body so as to generate friction with the ground outside the bridge body. The response displacement of a long bridge during an earthquake
It is significantly reduced by friction with the vibration damping device of the present invention. Since the size of the damping device is not limited, it is not necessary to use a large number of mechanical devices as in the related art, and the design margin of the bridge is greatly increased.

The use of frictional force for damping has a great theoretical effect. It is to be noted that in order to increase the friction of the sliding portion, it is possible to freely use an abrasive material or devise the surface shape.

[0011]

FIG. 1 is an explanatory view showing a vibration damping device for a bridge according to the present invention. The bridge body 1 is supported at both ends on a pier 2 and has a main tower 3
From the cable 4. As shown in FIG. 1, a vibration damping device 11 of the present invention is mounted on a bridge body 1 with a sliding surface 12 cut off from the edge of the bridge body 1 and a portion extended from the bridge body is ground. 13 with a fixing surface 14.

PC consisting of two continuous spans each having a span of 75 m
Implementation of the present invention by simulation for cable-stayed bridge
An example vibration analysis was calculated. Cable-stayed type of cable-stayed bridge is equivalent
Harp, the main tower is free,2%Expected structural damping of
Friction resistance was applied to the end of the spar. Road Bridge Specifications Class I Ground
forShakeA trial calculation was made using twice the dynamic acceleration.

The weight of the vibration damping device 11 is about 5% of the weight per unit length of the bridge. The vibration damping device 11 was constructed so as to be slidable on the main girder. When an acceleration of 0.2 G or more acts in the bridge axis direction, the vibration damping device 11 starts sliding on the main girder, and exerts a dynamic frictional resistance force on the main girder in a direction opposite to the relative movement direction. FIG. 3 shows the result of vibration analysis performed by simulation, assuming that the dynamic frictional resistance is μ = 0.2. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the acceleration of vibration (ACC: gal) and the vibration speed (VEL: kin).
e) is a chart showing displacement (DIS: cm).
In contrast to the speed curve 21 and the displacement curve 23 when there is no friction, the speed curve 22 and the displacement curve 24 when friction is considered.
It became like.

As is clear from FIG. 3, the maximum response displacement of the cable-stayed bridge having a length of 150 m was reduced by half from 25 cm to 14 cm. FIG. 2 shows that the vibration damping device 11 includes the bridge 1 and the fixed surface 1.
5 shows an example in which the sliding surface 16 is provided without being fixed to the ground 13.

[0015]

Since the bridge body vibration damping device of the present invention is constructed as described above, the displacement of the bridge body during an earthquake can be effectively reduced, and an accident such as a falling bridge can be prevented. It has an excellent effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is a side view showing a bridge body vibration damping device according to an embodiment of the present invention.

FIG. 2 is a side view showing a vibration damping device for a bridge according to an embodiment of the present invention.

FIG. 3 is a chart showing effects of the embodiment.

FIG. 4 is an explanatory diagram of a conventional vibration damping device.

FIG. 5 is an explanatory diagram of a conventional vibration damping device.

FIG. 6 is an explanatory diagram of a conventional vibration damping device.

[Description of Signs] 1 Bridge 2 Bridge pier 3 Main tower 4 Cable 11 Damping device 12, 16 Sliding surface 13 Ground 14, 15 Fixed surface 21, 22 Velocity curve 23, 24 Displacement curve 30, 40, 50 Seismic isolation device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeki Ungami, 1st Asahi, Asahi, Tsukuba, Ibaraki Prefecture Within the Public Works Research Institute, Ministry of Construction (72) Inventor Akihide Kubo 3-4-1 Marunouchi, Chiyoda-ku, Tokyo PS Inn Co., Ltd.

Claims (2)

(57) [Claims] Claims: 1. A sliding surface movably relative to a bridge along a bridge body to be damped, and extends outward in the bridge axis direction, and the extended portion is connected to an abutment and / or ground. A bridge body vibration damping device comprising a fixed vibration damping element. 2. A bridge body fixed to a bridge body to be damped, extending outwardly of the bridge body in the bridge axis direction, and a portion outside the bridge body is made of a vibration damping element contacting the ground with a sliding surface. Vibration control device.