Method of installing sound absorbing bodies on a sound insulation wall and an installed sound absorbing body assembly

First, sound absorbing plates made of a hard material are fixed to both side plates of shaped steel members extending upward from a sound insulation wall at intervals that are equal to arrangement spans of the shaped steel members. Then, sound absorbing members that have been formed into a predetermined shape and length are attached to outer surfaces of the sound insulation plates.

BACKGROUND OF THE INVENTION 
The present invention relates to an improvement in an installation method 
of sound absorbing bodies that are attached, to prevent diffraction of 
noise sound, to the top portion of a sound insulation wall which is 
installed to prevent diffusion of noise sound generated in an expressway, 
a factory, etc. 
A means for installing the above type of sound absorbing bodies to the top 
portion of a sound insulation wall is disclosed in "Improvements of Noise 
Reducer (Novel Sound Insulation Wall for Roads)" (in Japanese), 
Expressways and Automobiles, Vol. 36, No. 2, pp. 39-42, published by 
Express Highway Research Foundation of Japan on Feb. 1, 1993. 
As shown in FIG. 8, in the above conventional means, preliminarily formed 
sound absorbing body halves D and E are connected to side plates B and C 
of an H-shaped steel member A that projects upward from the top face of a 
sound insulation wall (not shown) with weld bolts F and nuts G. (One of 
the side plates B and C faces a sound source.) Each of the sound absorbing 
body halves D and E is prepared in advance such that a sound absorbing 
material J such as glass wool is interposed between an inner sound 
insulation plate H such as a steel plate and an outer perforated plate I, 
and then a resulting structure is formed into a predetermined shape and 
length. 
In the above conventional installation method, while the sound absorbing 
body halves D and E are preliminarily formed into a predetermined shape 
and length, in many cases the arrangement span of the H-shaped steel 
members A varies from one installation site to another. Where the 
arrangement span of the H-shaped steel members A does not conform to the 
length of the preliminarily formed sound absorbing body halves D and E, it 
is necessary to produce new sound absorbing body halves having suitable 
dimensions, or to adjust the length at an installation site. This results 
in ah increased cost, a complex installing operation, and other problems. 
SUMMARY OF THE INVENTION 
In view of the problems of the above-described conventional method, an 
object of the present invention is to provide an installation method which 
can install sound absorbing bodies which have been formed into 
predetermined dimensions relatively easily in an orderly manner, 
irrespective of the arrangement span of H-shaped steel members. 
According to the invention, a method of installing, on a top portion of a 
sound insulation wall, sound absorbing bodies that comprise right and left 
halves each comprising sound insulation plates made of a hard material and 
sound absorbing members, the right and left halves assuming a generally 
symmetrical shape with respect to a vertical plane when installed, 
comprises the steps of: 
fixing the sound insulation plates to right and left side plates of shaped 
steel members extending upward from the top portion of the sound 
insulation wall at intervals that are equal to arrangement spans of the 
shaped steel members; and 
attaching the sound absorbing members that have been formed into a 
predetermined shape and length to outer surfaces of the sound insulation 
plates.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1-7 show sound absorbing bodies that are attached to shaped steel 
members extending from the top face of a sound insulation wall according 
to an example of practicing of the present invention. A half of a sound 
absorbing body 1 used in practicing the invention consists of a sound 
insulation plate 2 that is an inner plate produced by forming a hard 
material such as a steel plate (see FIG. 2) and a sound absorbing member 6 
in which a sound absorbing material 4 such as glass wool is incorporated, 
by use of holding members 5, inside of a perforated plate 3 such as a 
polycarbonate plate having punched-out small holes (see FIG. 4). 
Although the illustrated sound absorbing member 6 consists of the 
perforated plate 3 and the sound absorbing material 4 such as glass wool, 
the invention imposes no limitations on the materials of the sound 
absorbing member 6. For example, it may be made only of a porous sintered 
metal, foamed aluminum or foamed ceramics (i.e., without using the 
perforated plate 3). 
As shown in FIGS. 1 and 2, the sound insulation plate 2 and the sound 
absorbing member 6 are so formed that a cross-section generally assumes a 
"?" shape, and two sets of sound insulation plate 2 and sound absorbing 
member 6 are connected to each other so as to be symmetrical with respect 
to a vertical plane. However, the invention is not limited to this 
structure, but the sound insulation plate 2 and the sound absorbing member 
6 may be so formed that a cross-section assumes a semi-circular or 
semi-elliptical shape as long as the two sets of sound insulation plate 2 
and sound absorbing member 6 can prevent diffraction of noise sound when 
they are connected to each other so as to be symmetrical. 
As shown in FIGS. 1 and 5, in the first step of the invention, bottom 
portions 10 and 11 of the sound insulation plates 2 are fixed, with weld 
bolts of side plates 8 and 9, to the outer faces of the side plates 8 and 
9 of each of shaped steel members 7 (in the illustrated example, H-shaped 
steel members) that extend upward from the top face of a sound insulation 
wall (not shown) and are arranged at predetermined spans. (One of the side 
plates 8 and 9 faces a sound source.) The sound insulation plates 2 may be 
fixed to the shaped steel members 7 with their length being so adjusted as 
to conform to the span of the shaped steel members 7. That is, the sound 
insulation plates 2 need not be formed preliminarily into a predetermined 
length. 
In a top portion 14 of the sound absorbing body 1 (see FIG. 1), extensions 
15 and 16 of the sound insulation plates 2 are placed on each other, and 
connected to each other by use of a clip nut 17 that is attached to the 
extension 16 and a bolt 18 (see FIGS. 1 and 3). Then, the resulting 
assembly is placed onto the shaped steel members 7 from above, and fixed 
thereto (see FIG. 1). 
Subsequently, in the second step, the sound absorbing members 6 are 
attached to the outer surface of the sound insulation plates 2 fixed to 
both sides of the shaped steel members 7. 
In the illustrated example (FIGS. 1 and 5), each sound absorbing member 6 
is fixed to a bottom extension plate 19 of the sound insulation plate 2 by 
engaging, through a water draining plate 21, a bolt 22 with a clip nut 20 
that is attached to the extension plate 19. But the invention is not 
limited to this fixing structure. 
As shown in FIGS. 1 and 3, in the top portion 14 of the sound absorbing 
body 1, connecting metal fittings 27 and 28 are fixed to opposed end 
portions 23 and 24 of the sound absorbing members 6 through the holding 
members 5. Extensions 29 and 30 of the metal fittings 27 and 28 are placed 
on each other, and connected to each other by use of a clip nut that is 
attached to the extension 30 and a bolt 32. Then, as described above, the 
connected sound absorbing members 6 are placed, from above, onto the sound 
insulation plates 2 that are fixed to the shaped steel members 7, and then 
fixed to the sound insulation plates 2. 
The sound absorbing members 6, each of which is so formed as to have a 
predetermined length L that is irrelevant to the span of the shaped steel 
members 7, are attached, as described above, to the outer surfaces of the 
respective sound insulation plates 2 that are fixed to the shaped steel 
members 7 so that flanges 33 and 34 are opposed to each other (see FIG. 
4). As a result of the opposed arrangement of the flanges 33 and 34, 
continuous gaps 35 develop generally vertically between the adjacent ones 
of the sound absorbing members 6, 6A and 6B (see FIG. 6). 
FIGS. 6 and 7 are a plan view and a side view, respectively, showing an 
arrangement of the sound absorbing bodies 1. It is clearly seen from these 
figures that the gaps 35 have a remarkable effect in design. Since the 
length L of the individual sound absorbing members 6 is set at a 
predetermined value that is irrelevant to the span of the shaped steel 
members 7, the completely assembled sound absorbing bodies 1 are always 
uniformly arranged and exhibit an orderly appearance even if the span of 
the shaped steel members varies from one installation site to another. 
As mentioned above, the sound absorbing member 6 is not limited to the 
combination of the perforated plate 3 and the sound absorbing material 4 
such as glass wool, but may be a formed product made only of a porous 
sintered metal, foamed aluminum or foamed ceramics. 
As described above, in the first step of the invention, only the sound 
insulation plates, which will be later hidden inside the sound absorbing 
bodies, are fixed to the shaped steel members at the intervals equal to 
the spans of the shaped steel members. Therefore, even if the span of the 
shaped steel members varies from one installation site to another, it is 
sufficient to prepare the sound insulation plates whose length conforms to 
the span of the shaped steel members, or to cut the sound insulation 
plates at an installation site so that their length conforms to the span 
of the shaped steel members. This will improve the ease of the operation 
of fixing the sound insulation plates. 
After the fixing of the sound insulation plates, in the second step, the 
sound absorbing members which have been formed into a predetermined shape 
and length that are irrelevant to the span of the shaped steel members are 
attached to the outer surfaces of the sound insulation plates. Therefore, 
the sound absorbing members having standard dimensions (including the 
length) can be used universally. This will not only improve the ease of 
the operation of attaching the sound absorbing members, but also enable 
provision of a sound absorbing body assembly having an orderly appearance. 
Further, the sound absorbing members can be attached simply by placing from 
above the right-side and left-side sound absorbing members that have been 
connected at the top end portion onto the sound insulation plates, and 
fixing the sound absorbing members to the sound insulation plates at the 
bottom end portions. This will further improve the ease of the operation 
of attaching the sound absorbing members.