JPH1181233A - Sound insulating structure of bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control heavy low tones emanating from a bridge. SOLUTION: A plurality of main girders extending along the longitudinal direction of a transport passage component member are arranged parallel to the cross direction of the transport passage component member below the transport passage component member, and a plurality of horizontal girders 4 formed by placing plate-shaped bodies upright between the main girders along the cross direction of the transport passage component member are arranged parallel to the longitudinal direction of the transport passage component member. When the transport passage component member is supported on bridge base material and noises produced in the bridge suspended between the bridge base materials are suppressed, a vibration control member 7 formed by laminating a sound absorbing layer 7a made of a soft elastomer and an outer surface layer 7b made of a hard material is fixed integrally with each horizontal girder 4 near the bridge base material in such a way that the sound absorbing layer 7a is losely contacted with the surface of the surface of the horizontal girder 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plurality of main girders extending along the longitudinal direction of a transport path component below a transport path component such as a road or a railroad in the width direction of the transport path component. Along with the main girder, a horizontal girder formed by erecting a plate-like body is provided along the width direction of the transport path component, and the transport path component is interposed between the bridge supports. The present invention relates to a soundproof structure of a bridge for suppressing low-frequency noise generated in a bridge that has been built.

[0002]

2. Description of the Related Art In recent years, noise generated from members of a transportation route has become a social problem. A noise barrier or the like is provided on the side of the members of the transportation route to reduce noise radiated to surrounding areas. Measures are being taken. However, low-frequency noise generated below the transport path components by such a method has not been fully addressed at present, and particularly, heavy bass noise generated by such a situation. As for, no effective soundproofing method is known.

[0003]

For this reason, heavy bass noise, which has been regarded as a problem in recent years, has been generated from the bridge main body in a state where the causal relationship cannot be specified.
There is a need for a technique for suppressing the occurrence of heavy bass from a bridge.

[0004] Therefore, an object of the present invention is to suppress heavy bass generated from a bridge in view of the above-mentioned current situation.

[0005]

In order to achieve the above object, the characteristic structure of the soundproofing structure of a bridge according to the present invention is that a main girder along the longitudinal direction of the transport path component is provided below the transport path component. A plurality of horizontal beams are arranged in parallel in the width direction of the transport path member, and a plate-like body is formed between the main girders along the width direction of the transport path member so as to be transported. A plurality of sound absorbing members made of a soft material are provided in parallel with each other in the longitudinal direction of the road component members to suppress noise generated in a bridge installed between the bridge support members by supporting the transport path member members on the bridge support members. A vibration damping member formed by laminating a layer and an outer layer made of a hard material is integrally fixed to a cross beam near the bridge support so that the sound absorbing layer is in close contact with the cross beam side surface. . It is preferable that the soft material is at least one selected from a soft elastomer and a lead plate, and it is preferable that the soft elastomer is mainly composed of chloroprene rubber. It is preferable that the sound absorbing layer is formed by laminating a plurality of soft materials having different hardnesses. Further, it is desirable that the sound absorbing layer is interposed between the outer surface layer and the cross beam in a compacted state, and the hard material is desirably an iron plate.

[Effects] The present inventors have searched for a portion that is a noise source on the lower surface side of the bridge in accordance with the above-mentioned current situation. When an object is transported and passes over the bridge support,
It has been found that the horizontal girder near the bridge support receives the vibration of the transported object and generates a low frequency vibration sound of about 50 Hz to about 1000 Hz. At the same time,
Even on the side of the main girder and the bottom of the box girder, it has been found that it is hardly affected by vibration except for the area very close to the bridge support, and does not cause noise. The present invention is based on these new findings. In other words, normally, when the noise source is specified to be on the lower side of the bridge, it is considered that long-period vibration is generated due to the vibration of the bridge as a whole. Is expected to be a noise source. To give a concrete example, vibration generated when a car passes over a pier on a motorway is absorbed by the cross beam on the pier or at a position very close to the pier, and becomes a noise source because it resonates. It was.

[0007] For this reason, as a general anti-vibration measure, it is conceived that the sound is shielded by covering the entire underside of the bridge, but at least the horizontal girder specified as a noise source is used as the anti-vibration measure. To find something good to do.

In order to take measures against vibrations of the cross beam, first, a method of integrating a heavy object with the cross beam as a vibration control technique is conceived. In order to attach another object, it is necessary to lift the other object to the position of the cross beam, and it takes a lot of effort to lift a heavy object required for the vibration control technique, which is not realistic. It is also conceivable that a curable material such as concrete is integrally cured with the cross beam. However, although the conditions are reduced in terms of weight, the curable material having fluidity is used. This causes a problem in the technique of holding the resin until it cures.

On the other hand, if a sound absorbing layer made of a soft material is provided integrally with the cross beam, the sound absorbing layer greatly attenuates the vibration of the cross beam and suppresses the generation of noise. Can be expected. Further, if an outer surface layer made of a hard material is laminated on the sound absorbing layer and the sound absorbing layer is integrally fixed so as to be in close contact with the cross beam side surface, the vibration propagated to the sound absorbing layer is first transmitted to the sound absorbing layer. The vibration energy is transmitted to the hard material while being attenuated by being converted into deformation, heat generation, and the like by the sound absorbing layer. The vibration that has reached the hard material is reflected by the difference in material from the vibration source, and returns to the inside of the sound absorbing layer again. Further, for the same reason, it is considered that the vibration reflected in the sound absorbing layer reciprocates between the cross beam and the hard material, and is consumed and disappears in the sound absorbing layer. Therefore, the vibration transmitted to the cross beam is attenuated from the cross beam or the hard member to the amount transmitted to the air layer without being released to the sound absorbing layer, and is effectively soundproofed. become.

As the soft material, a soft elastomer,
A lead plate exhibits a sufficient sound absorbing effect, and can effectively absorb noise at a frequency corresponding to the characteristics of the soft material. In addition, when the sound absorbing layer is formed by laminating a plurality of soft materials having different hardnesses, it can absorb noise in a wide frequency band, or is suitable for frequency characteristics of vibration generated in each part. The selected sound absorbing layer can be selectively used, so that noise can be more appropriately absorbed.

When the sound absorbing layer is interposed between the outer surface layer and the cross beam in a compact state, the vibration transmitted into the sound absorbing layer is less likely to be transmitted to the air layer, and the soundproofing effect is particularly enhanced. it can.

Further, if the soft elastomer is mainly composed of chloroprene rubber, it has excellent sound absorption characteristics. If the hard material is an iron plate, it easily reflects vibration transmitted from the soft elastomer, and As a load mass, it also functions as a vibration damping material, and has sufficient strength to withstand the sound absorbing layer even if it is tightened with a bolt and nut in order to interpose the sound absorbing layer in the horizontal beam in a compact state.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the bridge shown in Figs. 1 and 2,
Below the slab 2 forming the road 1 as a transport path constituent member, an I getter 3a formed by erecting an I-section steel along the longitudinal direction of the road 1 is provided, and a part thereof is formed of a steel plate. To provide a box girder 3b formed in a covering box shape by
A main girder 3 is formed, and a plurality of the main girder 3 are arranged side by side in the width direction of the road 1, and between the main girder 3 along the width direction of the road 1,
A plurality of cross beams 4 formed by erected I-section steel are arranged in parallel in the longitudinal direction of the road 1, and the road 1 is supported by a pier 5 as a bridge support, and erected between the piers 5. It is. The soundproofing structure for a bridge according to the present invention includes the pier 5
As shown in FIG. 3, a vibration damping member 7 is integrally formed on both sides of a central portion of the cross beam 4 erected right above the flat member 4 in a plan view, as shown in FIG. The vibration damping member 7 includes:
As shown in FIG. 3, the sound absorbing layer 7 made of a soft elastomer
a and an outer layer 7b made of a hard material are laminated, and the sound absorbing layer 7a is formed of a first sound absorbing layer 7A made of a soft elastomer.
Then, a second sound absorbing layer 7B made of a lead plate is laminated in this order from the cross beam 4 side in the order of the second sound absorbing layer 7B and the first sound absorbing layer 7A. Further, through holes 7c penetrating the front and back are provided at several places in plan view, and bolt nuts 6 are used on both sides of the cross beam 4 so that the sound absorbing layer 7a is in close contact with the surface of the cross beam 4 side. It is formed to be freely fixed.

[Another embodiment]
Instead of the one that forms the motorway 1, it may be one that forms a railroad, that is, any one that corresponds to a bridge that can generate vibrations when the transported object is transported upward. In the above-described embodiment, the main girder is provided with the box girder. However, a bridge having only the I-getter may be used, and the present invention can be applied to a bridge in which the horizontal girder is provided near the bridge supporting member. Further, instead of fixing the damping member to the cross beam with a bolt and nut, it is also possible to bond the damping member. However, it is preferable to interpose the sound absorbing layer between the outer surface layer and the cross beam in a compacted state by using a bolt and a nut or the like, since sound absorbing characteristics are improved. For the outer layer, a metal plate such as an iron plate or a lead plate, a hard ceramic, a hard resin, or the like can be used, but when the sound absorbing layer is fixed in a dense state, for example, when it is fixed with a bolt and a nut. However, the metal plate can be used effectively. Further, the vibration damping member 7 may be provided only on one side of the cross beam 4, or may be provided on both sides. Further, the sound absorbing layer 7a may be formed of only one layer made of a soft elastomer, or may be formed in a multilayer. (See Fig. 4)

[0015]

Embodiments of the present invention will be described below with reference to the drawings. A, B, C in FIG. 1 near the pier 5 of the bridge
FIG. 5 shows the state of noise generation at each point. The noise generation status was obtained as an arithmetic average of the generated sound pressures after passing ten passenger cars on the road 1 on the pier 5. As a result, the sound pressure level in the low-tone range measured at the center of the cross beam 4 in plan view is particularly high, and it is understood that this is a particularly problematic source of low-frequency noise.
Therefore, when the damping members 7 having various shapes were fixed at the point A, the attenuation of the generated sound was compared with the noise generated when only the cross beam 4 was used. Was.

[0016]

[Table 1] CR: Chloroprene rubber U: Foamed polyurethane

As a result, it can be seen that the vibration damping member 7 in which the sound absorbing layer 7a and the outer surface layer 7b are combined exhibits high sound absorbing characteristics and a high soundproofing effect can be expected.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a bridge.

FIG. 2 is a longitudinal sectional side view of a main part of a bridge.

FIG. 3 is a longitudinal sectional side view in a state where a vibration damping member is mounted.

FIG. 4 is a longitudinal sectional side view of an example of a mounting state of a vibration damping member according to another embodiment.

FIG. 5 is a graph showing the results of a vibration test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Road 2 Floor slab 3 Main girder 3a I getter 3 Box girder 4 Cross girder 5 Bridge pier 6 Bolt nut 7 Damping member 7a Sound absorption layer 7b Outer surface layer 7c Through hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seiji Ishii 1-1-57 Shibaya, Suminoe-ku, Osaka-shi, Osaka Inside Mitsui Engineering & Shipbuilding Corporation (72) Inventor Shingo Watari 516 Kamino, Sakai-shi, Osaka Tokawa Rubber Co., Ltd. (72) Inventor Toshio Toyoda 4-5-2-5 Minamihorie, Nishi-ku, Osaka-shi, Osaka Togawa Rubber Co., Ltd. In the rubber

Claims (6)

[Claims] 1. A plurality of main girders along the longitudinal direction of a transport path component member are arranged below the transport path component member in the width direction of the transport path component member, and the main beam is transported between the main girders. A plurality of cross girders formed by erected plate-like bodies are arranged in the longitudinal direction of the transport path component along the width direction of the path component, and the transport path component is supported by a bridge support. A soundproofing method for a bridge that suppresses noise generated on a bridge installed between the bridge supports, wherein the vibration-damping member is formed by laminating a sound-absorbing layer made of a soft material and an outer layer made of a hard material. The sound absorbing structure of a bridge in which the sound absorbing layer is integrally fixed to a cross beam near the bridge support so that the sound absorbing layer is in close contact with the cross beam side surface. 2. The soundproofing structure for a bridge according to claim 1, wherein the soft material is at least one selected from a soft elastomer and a lead plate. 3. The soundproofing structure for a bridge according to claim 2, wherein the soft elastomer is mainly made of chloroprene rubber. 4. The soundproof structure for a bridge according to claim 1, wherein the sound absorbing layer is formed by laminating a plurality of soft materials having different hardnesses. 5. The sound absorbing layer according to claim 1, wherein the sound absorbing layer is interposed between the outer surface layer and the cross beam in a compacted state.
The soundproofing structure of the bridge described in the paragraph. 6. The soundproofing structure for a bridge according to claim 1, wherein the hard material is an iron plate.