JP4301408B2 - Impact sound insulation type double structure - Google Patents

Description

  The present invention relates to an impact sound insulation type dual structure, and more particularly to a structure for improving the impact sound insulation performance of a double floor or ceiling in which a panel material is supported above or below a floor base of a structure via a gap.

  In apartment houses such as apartments and condominiums, as shown in FIG. 7, a floor board 3 such as a particle board is supported on a floor base 2 such as a concrete slab by a support leg 10 with an elastic pedestal 13 whose height can be adjusted. Double floors on which flooring materials and other finishing materials are laid are widely used. The double-floor structure can easily obtain a floor surface with a uniform height compared to the direct-bonding structure in which the finishing material is laid directly on the floor base 2, and the work such as piping and wiring is performed by the gap 6 under the floor. There is an advantage that an appropriate feeling of walking can be obtained by the elastic base 13 and a direct impact to the floor base 2 can be prevented. However, the double floor structure may not be able to sufficiently block the floor impact sound on the upper and lower floors, and particularly heavy floor impact sound with a large impact force (for example, the falling sound of heavy objects on the upper floor and the jumping of people) The blocking performance against sound, etc.) may be reduced by as much as 10 dB compared to the direct attachment structure. The double floor structure has relatively good shielding performance against light floor impact sounds with low impact force (for example, falling sounds of lightweight objects on the upper floor and moving sounds of chairs, etc.), and carpets, tatami mats, etc. Can be improved relatively easily by using a soft finish.

  The mechanism of the heavy floor impact sound cutoff performance degradation in the double floor structure is not completely clarified, but in general, the elements constituting the double floor, that is, the elasticity of the elastic base 13 and the elasticity of the gap 6 ( This is due to the amplification of floor impact sound due to the resonance system (hereinafter referred to as the double floor resonance system) composed of the rigidity of the floor board 3, the mass of the floor board 3, etc. It is considered that the amplification of the band is the main cause of the decrease in the performance of blocking the heavy floor impact sound. Although it is conceivable to suppress the amplification of heavy floor impact sound by measures such as increasing the thickness of the floor base 2, such measures are difficult to implement due to excessive structural loads, and structural design changes Is not easy. For this reason, various other measures for suppressing amplification of heavy floor impact sound have been proposed.

  For example, in Patent Document 1, a slight gap is provided between the floor 3 of the double floor and the wall around the double floor, and the air is released from the gap 6, thereby suppressing the influence of the air spring and amplifying the impact sound. Disclosed is a sound insulation floor structure that suppresses noise. However, the structure of Patent Document 1 is effective when the floor area is relatively small. However, when the floor area is large, the effect of removing air is relatively small, and the effect of blocking the impact sound cannot be expected. Moreover, since the clearance gap provided in the circumference | surroundings of the floor board 3 becomes a problem on an architectural design, there is also a problem that finishing of the circumference of the floor board 3 is difficult and time-consuming work is required. Recently, there is a tendency to increase the use of large slabs that can form large spaces without pillars and beams, and there is a need for heavy floor impact sound insulation technology that can be easily applied to double floors with large floor areas. .

  As an impact sound blocking technique applicable to a double floor having a relatively large floor area, Patent Document 2 discloses a method for preventing amplification of heavy floor impact sound by softening the hardness of the elastic base 13 of the support leg 10. is suggesting. Further, Patent Document 3 lays a large mass damping and sound insulation sheet such as a metal powder-containing asphalt sheet between the floor plate 3 having a double floor structure and the finishing material, and the mass and rigidity of the entire double floor resonance system. We propose a method to prevent amplification of heavy floor impact sound by increasing

JP 2002-349052 A JP 2003-268932 A Japanese Patent Laid-Open No. 10-259658 JP 2000-179134 A Edited by Ho Nagata, “Acoustics Engineering Lecture 3, Architectural Acoustics, Chapter 4 Acoustic Materials”, Corona, March 1988, p68-73

  When the double floor structure forms an ideal one-mass point resonance system as shown in FIG. 8A described later, the resonance frequency can be shifted to a sufficiently low range by the method of Patent Document 2 or 3. As a result, it is expected to improve the floor impact sound blocking performance. However, as described above, the actual double floor resonance system is complex, and the heavy floor impact sound is amplified in a wide band of about 31.5 to 250 Hz. Therefore, the methods of Patent Documents 2 and 3 simply set the resonance frequency. It may not be possible to shift to a sufficiently low range, and it may be difficult to improve the performance of blocking heavy floor impact sound.

  In the method of Patent Document 2, if the elastic pedestal 13 is too soft, the bending (displacement) of the floor board 3 and the support leg 10 becomes large when a load is applied, and the displacement of the storage part of the floor board 3 and the inclination of the furniture on the floor board 3 and the like. Will occur. Accordingly, it is difficult to shift the resonance frequency to a sufficiently low range, and it is difficult to improve the performance of blocking heavy floor impact sound. The method of Patent Document 3 also shifts the resonance frequency of the double floor structure to a sufficiently low range as long as the weight and rigidity of the vibration-damping and sound-insulating sheet are increased within a common sense that does not cause an excessive load on the structure. It is not possible to cope with the interruption of heavy floor impact sound. The band in which the heavy floor impact sound is amplified can vary depending on the main structure of the structure, the structure / configuration of the double floor, and the like. In order to cope with various structures and double floors, it is necessary to be able to block broadband heavy-weight floor impact sounds.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an impact sound cutoff type double structure capable of blocking a heavy floor impact sound over a wide band.

  In the double floor structure as shown in FIG. 7, the inventor gives a damping force to the gap 6 (air layer) having almost no loss, and suppresses the floor vibration transmissibility in the double floor resonance system. noticed. In general, a one-mass spring-mass resonance system formed by an elastic body (hereinafter referred to as viscoelastic body) having a spring constant k and a loss coefficient η and a mass m is modeled as shown in FIG. It is known that the vibration transmissibility T can be expressed as shown in the graph of FIG.

As can be seen from the graph of FIG. 8B, when the loss coefficient η of the viscoelastic body is as small as air, the frequency ω of the floor impact sound is almost the same as the resonance frequency ω ₀ of the double floor structure (frequency When the ratio ω / ω ₀ ≈1) and the vibration transmissibility T is increased and the floor impact sound is amplified, and the frequency ω of the floor impact sound is sufficiently larger than the resonance frequency ω ₀ (frequency ratio ω / ω ₀ > In the case of 2 ^1/2 ), the vibration transmissibility T becomes small and the floor impact sound is cut off. The method of Patent Document 2 and 3, by shifting the resonance frequency omega ₀ of the double floor structure to the low frequency side, the vibration transmissibility T of heavy floor impact sounds of the frequency omega close to the resonance frequency omega ₀ of the previous shift It can be said that the technology to make it smaller. However, in the actual double floor structure, the floor impact sound is not amplified only at the single resonance frequency ω ₀ as in the model shown in the figure, but the floor impact sound is amplified in a wide band as described above.

  As a conventional method for applying a damping force to the air gap 6 to block floor impact sound, for example, as disclosed in Patent Document 4, a fiber-based porous sound absorbing material such as glass wool and rock wool is used in the air gap 6 having a double floor structure. A method of spreading is known. In this method, for example, the air vibration (pressure fluctuation) of the floor impact sound generated on the upper floor of the double floor structure is blocked by absorbing the sound by the viscous friction of the porous sound absorbing material in the gap 6. However, according to the experience of the present inventors, the porous sound-absorbing material is effective in blocking a relatively high-frequency sound, but the effect of blocking a low-frequency sound (heavy floor impact sound) cannot be expected so much. In Patent Document 4, a predetermined width and a predetermined ratio of passages are provided between sound absorbing materials to improve the effect of blocking heavy floor impact sound. It has also been experienced when the heavy floor impact sound of a floor structure is amplified by a sound absorbing material.

The graph of FIG. 8B shows that the vibration transmissibility T of the double floor structure can be reduced by increasing the loss factor η without shifting the resonance frequency ω ₀ . The present inventor does not give an acoustic damping force to the gap 6 having a double floor structure by viscous friction as in the sound absorbing material, but the Young's modulus is equal to or slightly higher than that of the air layer as shown in FIG. If the gap 6 of the fluid medium having a double floor structure is replaced by a solid medium viscoelastic material having a high coefficient η and the floor base 2 and the panel material 3 are mechanically coupled, the vibration transmissibility T can be kept small over a wide band. We obtained the knowledge that it is expected to improve the performance of blocking heavy floor impact sound over a wide band. The present invention has been completed as a result of research and development based on this finding.

Referring to the embodiment of FIG. 1, the impact sound cutoff type double structure of the present invention is such that the panel material 3 is opposed to the floor base 2 of the structure via a gap 6 (see FIG. 7). supporting, loss factor provided in voids within 6 eta is high and the Young's modulus _{E, rib} binds the floor foundation 2 and the panel member 3 via a substantially equal or slightly higher viscoelastic body 8 thereto of air, dual By adjusting the cross-sectional area s of the viscoelastic body and / or the number n of viscoelastic body groups with respect to the total floor area A of the double structure so that the resonance frequency ω ₀ of the structure does not substantially change depending on the presence or absence of the viscoelastic body 8. It will be. Preferably, a plurality of viscoelastic bodies 8 having a columnar shape, a truncated cone shape (see FIG. 5), or a beam shape (see FIG. 2) are provided in the gap 6.

  For example, the floor base 2 and the panel material 3 are joined by pressing the floor base 2 and the panel material 3 to both ends of the viscoelastic body 8. Further, as shown in FIG. 2, one end of the viscoelastic body 8 is fixed to the floor base 2 or the panel material 3 with a thick adhesive 9, and the floor of the viscoelastic body 8 is adjusted via the adjustment of the thickness of the adhesive 9. The base 2 and the panel material 3 may be combined. The viscoelastic body 8 can be made of one or more materials selected from the group of foamed plastic, silicon rubber, glass wool or rock wool.

The impact sound insulation type double structure of the present invention supports the panel material via a gap above or below the floor base of the structure, and the loss coefficient η provided in the gap is high, and the Young's modulus E _rib is equivalent to air The viscoelastic body with respect to the total floor area A of the double structure so that the floor base and the panel material are coupled via the viscoelastic body so that the resonance frequency ω ₀ of the double structure does not substantially change depending on the presence or absence of the viscoelastic body. Since the cross-sectional area s and / or the number n of viscoelastic body groups is adjusted , the following remarkable effects are obtained.

(A) Since the vibration transmissibility of the heavy floor impact sound is suppressed by the viscoelastic body, it is possible to improve the performance of blocking the heavy floor impact sound over a wide band.
(B) In addition to the conventional 63Hz band, which is the determination frequency for heavy floor impact sound levels, it is possible to improve the performance of blocking heavy-weight floor floor impact sounds from the lower 31.5Hz to 250Hz bands. In addition, a general-purpose dual structure that can appropriately cope with various heavy floor impact sounds that can change depending on the main structure of the structure, the floor structure, and the like.
(C) By making the Young's modulus E _rib of the viscoelastic body substantially equal to or slightly higher than that of air, it is possible to improve the performance of blocking heavy floor impact sound without impairing the advantages of the conventional double floor structure. .
(D) For example, a viscoelastic body is appropriately arranged in a gap between the floor base and the panel material in the form of a column, frustum or beam, and the viscoelastic body is relatively pressed and bonded to the floor base and the panel material. With a simple work, a double structure with a large floor area can be easily constructed.

(E) By supporting the upper load with the support legs with the elastic base as in the conventional double floor structure, problems such as deterioration of walking feeling and inclination of furniture due to bending can be avoided.
(F) By using an inexpensive viscoelastic material such as foamed plastic instead of an expensive material as in the conventional vibration-damping and sound-insulating sheet, it is possible to economically improve the insulation performance of heavy floor impact sound.
(G) Not only the double floor structure above the floor base but also the ceiling structure below the floor base can be applied.
(H) When applied to a double floor in front of a floor in a large slab that has been increasing in recent years (a method of constructing a floor prior to a partition wall in a dwelling unit), the connection between the viscoelastic body and the floor base is a double floor. Since it acts as a damping mechanism with a constraining layer for vibration propagation on the surface, it is possible to reduce the double floor bodily sensation vibration that is likely to occur in the same dwelling unit.

FIG. 1 shows an embodiment in which the double floor structure of the present invention is constructed on a floor base 2 made of reinforced concrete in this case. The illustrated double floor structure 1 includes a plurality of support legs 10 provided on a floor base 2 at appropriate intervals, and a panel material (base panel) 3 supported on the support legs 10 so as to face the floor base 2. And a viscoelastic body 8 that couples the floor base 2 and the panel material 3 to be interposed in the gap 6 between the floor base 2 and the panel material 3. The viscoelastic body 8 has a Young's modulus E _rib equal to or slightly higher than that of the air layer and a high loss factor η. Hereinafter, the present invention will be described based on the illustrated double floor structure 1, but the present invention is not limited to the application to the floor structure, and the panel material 3 is supported opposite to the floor base 2 through a gap. It can be applied to a ceiling structure (hereinafter sometimes referred to as a double ceiling structure). Even when applied to a double ceiling structure, those skilled in the art should apply the following explanations except that the panel material 3 is supported below the floor base 2 and the support legs 10 are replaced by suspension bolts. Will be fully understood.

  As shown in FIG. 7, the support leg 10 in the illustrated example includes a leg portion 12 that can be adjusted in height, a panel receiving portion 11 provided at the top end, and an elastic pedestal 13 provided at the bottom end. In the illustrated double floor structure 1, a plurality of support legs 10 are evenly arranged on a floor base 2, and a rib-like viscoelastic body 8 (hereinafter referred to as viscoelasticity) slightly higher than the support legs 10 between the support legs 10. Rib 8)), and the panel material 3 is placed horizontally on the panel receiving portion 11 of the supporting leg 10 and is compression-bonded to the viscoelastic rib 8 so that the viscoelastic rib 8 is interposed. The floor base 2 and the panel material 3 are combined. If necessary, the joist member 5 may be provided as in the illustrated example, and the panel member 3 may be installed on the panel receiving portion 11. The panel material 3 is opposed to the floor base 2 by the support legs 10 so as to be point-like, and parts other than the supported points of the floor base 2 and the panel material 3 are connected by the viscoelastic ribs 8. However, the panel material 3 is not limited to the support by the support legs 10 and can be supported by using another appropriate support member belonging to the prior art. Although there is no restriction | limiting in particular in the material of the panel material 3, Generally, it is a product made from a particle board. On the panel material 3, a flooring material, a carpet, a finishing material such as a tatami mat, a sound insulating sheet, or the like is laid as necessary. Upper loads such as the panel material 3, the finishing material, and the sound insulating sheet are supported by the support members such as the support legs 10 as in the case of a normal double floor.

An enlarged view of the viscoelastic rib 8 used in FIG. 1 is shown in FIG. The viscoelastic rib 8 in the figure is formed by forming a viscoelastic material having a Young's modulus E _rib equal to or slightly larger than that of air and having a high loss factor η into a truncated pyramid or truncated cone shape, and is slightly larger than the width of the gap 6. Has a large height. The viscoelastic rib 8 has a bottom end placed on the floor base 2 and a top end that is pressed by the weight of the panel material 3 when the panel material 3 is installed and is slightly compressed in the height direction. The substrate 2 and the panel material 3 are mechanically coupled. The viscoelastic rib 8 has a truncated pyramid shape or a truncated cone shape, so that compression of the top end is facilitated. However, the total spring constant of the viscoelastic rib 8 is not significantly larger or smaller than that of air. If the ratio of the total cross-sectional area and / or the total number of the viscoelastic ribs 8 is appropriately set, the shape of the viscoelastic ribs 8 is not particularly limited. For example, the viscoelastic ribs 8 may be prismatic or cylindrical. . When the floor base 2 and the panel material 3 are arranged to face each other, for example, by attaching an elastic base 13 to the floor base 2 so that the double floor does not rise due to the repulsive force of the viscoelastic rib 8, the width of the gap 6 therebetween The floor base 2 and the panel material 3 may be joined by inserting a viscoelastic rib 8 having a slightly larger height into the gap 6.

  FIG. 2 shows an embodiment of a viscoelastic rib 8 in which a viscoelastic material having a loss coefficient η is formed into a beam shape. The viscoelastic rib 8 has a bottom end (top end in the case of a ceiling structure) fixed on the floor base 2 by an appropriate adhesive 9 and a top end (bottom end in the case of a ceiling structure) pressed against the panel material 3. Thus, the floor base 2 and the panel material 3 are mechanically coupled. For example, the thickness of the beam-like viscoelastic rib 8 is made slightly larger than the width of the gap 6, and the panel material 3 is slightly compressed by the installation of the panel material 3 as in the case of FIG. Further, by using a thick wet adhesive 9 such as GL bond or mortar, the height is adjusted by the thickness of the adhesive 9 even if the thickness of the viscoelastic rib 8 is less than the width of the gap 6. The floor base 2 and the panel material 3 can be mechanically coupled by the viscoelastic rib 8. The top end of the viscoelastic rib 8 may be bonded to the panel material 3 with an adhesive 9. As can be seen from this embodiment, the shape of the viscoelastic rib 8 (for example, the width and thickness of the viscoelastic rib 8) can be arbitrarily selected if the total spring constant of the viscoelastic rib 8 is appropriately designed.

The viscoelastic rib 8 mechanically couples the floor base 2 and the panel material 3 to give a loss factor η to the double floor resonance system. The resonance system of the double floor structure 1 to which the loss coefficient η is given can be modeled as shown in FIG. 8 described above, and the weight floor at the resonance frequency ω ₀ of the double floor structure 1 according to the loss coefficient η. Amplification of impact sound (increase in vibration transmission rate T) is suppressed to a small level, and the performance of blocking heavy floor impact sound is enhanced. In order to improve the shut-off performance, it is preferable to increase the loss coefficient η of the viscoelastic rib 8 as much as possible. The Young's modulus E _rib of the viscoelastic rib 8 is preferably selected so as to be substantially equal to or slightly higher than that of air (= 1.4 × 10 ⁵ N / m ² ). It is desirable to set it within a double range, for example, about 2 × 10 ^{5 to} 9 × 10 ⁵ (N / m ² ). If the Young's modulus E _rib of the viscoelastic rib 8 is too large as compared with air, the resonance frequency ω ₀ of the double floor structure 1 may change to a high range and adversely affect the lightweight floor impact sound. By setting the viscoelastic rib 8 to have a Young's modulus E _rib equivalent to air, the resonance frequency ω ₀ of the double floor structure 1 is increased only by the loss coefficient η without greatly changing from the case where the viscoelastic rib 8 is not provided. A heavy floor structure 1 can be obtained.

As the material of the viscoelastic rib 8, an appropriate material having the above-described high loss factor η and Young's modulus E _rib equivalent to air can be selected. However, an example of a preferable material is an impact with a large displacement such as a heavy floor impact sound. And foamed polyethylene and other foamed plastics that exhibit a high loss factor, and silicon-based materials such as silicon rubber. Foamed plastic also has an advantage that Young's modulus E _rib can be finely adjusted by changing the expansion ratio. It is also possible to use a fibrous porous material such as glass wool or rock wool as the viscoelastic rib 8. In this case, the fiber-based porous material is used as a mechanical damping material that is mechanically coupled to the floor base 2 and the panel material 3, and is used as an acoustic damping material that absorbs impact sound by viscous friction as in Patent Document 4. This is completely different from the heavy floor impact sound blocking action.

In order to improve the performance of blocking the heavy floor impact sound of the entire double floor, it is desirable to arrange the viscoelastic ribs 8 uniformly in the gap 6. Further, it is preferable to replace as many voids 6 as possible with viscoelastic ribs 8 in order to improve the performance of blocking heavy floor impact sound. The present inventor replaces about 20% of the total floor area of the double floor structure 1 with the viscoelastic rib 8 when the viscoelastic rib 8 is made of a foamed plastic whose Young's modulus E _rib is about five times that of air. Thus, it was confirmed experimentally that it is effective in improving the performance of blocking heavy floor impact sound.

Furthermore, in the double floor structure 1 of the present invention, when a viscoelastic rib 8 (for example, a cylinder, a square pillar, etc.) having a Young's modulus E _rib slightly higher than that of air and a uniform cross-sectional area s is used, a double floor is used. The cross-sectional area s and / or the viscoelastic ribs of the viscoelastic ribs 8 depends on the total floor area A of the double floor structure 1 so that the resonance frequency ω ₀ of the structure 1 does not change substantially depending on the presence or absence of the viscoelastic ribs 8. The number n of groups can be adjusted. Practically, the resonance frequency ω ₀ of the double floor structure 1 using the viscoelastic rib 8 with Young's modulus E _rib is considered to correspond to the right side of the equation (1). What is necessary is just to determine the cross-sectional area s and the number n of the viscoelastic rib 8 so that it may not remove | deviate. In equation (1), ρ ₀ represents the density of air in the gap 6 and c ₀ represents the speed of sound in the air.

[Experiment 1]
In order to confirm the effect of blocking the floor impact sound by the double structure of the present invention, a test body of the double floor structure 1 shown in FIG. 1 is manufactured, and the test body of the floor base 2 only and the viscoelastic rib 8 are not provided. A test specimen was manufactured, and the floor impact sound was blocked using the test building 20 divided into a sound source room (upper room) 21 and a lower sound receiving room (lower room) 22 as shown in FIG. The experiment which compares was conducted. As the test body having only the floor base 2, the floor base 2 having the thickness shown in Table 1 was used. The test body without the viscoelastic rib 8 is supported by the support leg 10 with the floor base 2 and the panel material 3 having the thickness shown in Table 1 facing each other with the width of the gap 6 shown in the same table. A finishing material (flooring material) having a thickness shown in the table and a sound insulating sheet were laid. The specimen of the double floor structure 1 of the present invention is a foamed plastic having a loss factor η = 0.2 and Young's modulus E _rib = 5 × 10 ⁵ (N / m ² ) in the gap 6 of the specimen without the viscoelastic rib 8. The viscoelastic ribs 8 were arranged so that the total horizontal sectional area was approximately 20% of the total floor area.

  A test body having only the floor base 2, a double floor structure test body without the viscoelastic rib 8, and a double floor structure test body of the present invention are placed between the upper chamber 21 and the lower chamber 22 of the experimental building 20 in FIG. The floor generated by striking the panel material 3 or the floor base 2 with the floor impact sound generator 23 (tapping machine for generating lightweight floor impact sound or bang machine for generating heavy floor impact sound) in the upper chamber 21 The sound pressure level of the impact sound was measured by the microphone 24 in the lower chamber 22 and analyzed by the sound receiving device 25. The floor impact sound level was measured in accordance with JIS A1418 (method for measuring floor impact sound level at the building site). The experimental results are shown in the graphs of FIGS. FIG. 3 shows the experimental results of the performance of blocking the lightweight floor impact sound of the three specimens, and FIG. 4 shows the experimental results of the performance of blocking the heavy floor impact sound. The experimental result indicates an average value of sound pressure levels measured at a plurality of locations in the lower chamber 22.

  From the experimental results of FIG. 4, the amplification amount of the heavy floor impact sound level of the double floor structure test body with respect to the test body having only the floor base 2 is larger than that of the double floor structure test body without the viscoelastic rib 8. It can be seen that the double-floor structure test specimen improved by 1.5 dB in the 63 Hz band, 5 dB in the 125 Hz band, and 4.2 dB in the 250 Hz band. In other words, it was confirmed that the double floor structure 1 of the present invention can suppress the amplification of the heavy floor impact sound at the resonance frequency and improve the blocking effect of the heavy floor impact sound over a wide band. In the double floor structure used in this experiment, there was no amplification in the 31.5 to 63 Hz band even when there was no viscoelastic rib, so the effect of the viscoelastic ribs did not appear significantly in the 31.5 to 63 Hz band. In the heavy floor structure, the heavy floor impact sound is often amplified in the 31.5 to 63 Hz band, and it can be assumed that the double floor structure 1 of the present invention similarly acts on such amplification in the 31.5 to 63 Hz band. Further, the experimental results in FIG. 3 show that the light floor impact sound level of the double floor structure test body of the present invention is equal to or higher than that of the double floor structure test body without the viscoelastic ribs 8. . That is, it has been confirmed that the double floor structure 1 of the present invention can provide a light floor impact sound shielding performance equivalent to or higher than that of the conventional double floor structure.

  Thus, the provision of the “impact sound blocking type double structure capable of blocking heavy floor impact sound over a wide band”, which is an object of the present invention, can be achieved.

It is explanatory drawing of one Example of this invention. It is explanatory drawing of the other Example of this invention. It is an example of the graph which shows the interruption | blocking performance of the lightweight floor impact sound by the double floor structure of this invention. It is an example of the graph which shows the interruption | blocking performance of the heavy floor impact sound by the double floor structure of this invention. It is explanatory drawing of an example of the viscoelastic rib used by this invention. It is explanatory drawing of the experimental apparatus which measures the interruption | blocking performance of a floor impact sound. It is explanatory drawing of an example of the support leg which supports a panel material on a floor base. It is explanatory drawing of the vibration transmissibility of the spring-mass resonance system comprised with the viscoelastic body which has the elasticity k and loss factor (eta), and the mass m.

Explanation of symbols

1 ... Double structure 2 ... Floor base (slab)
3. Panel material (floor board)
5 ... joist member 6 ... void 8 ... viscoelastic body (rib) 9 ... adhesive
10 ... Support legs 11 ... Panel receiver
12 ... Leg 13 ... Elastic base
20… Experiment building 21… Upper room (sound source room)
22… Lower chamber (sound receiving room) 23 point impact sound generator
24 ... Microphone 25 ... Sound receiver

Claims (6)

A panel material is supported on or under the floor base of the structure via a gap, and a viscoelastic body having a high loss coefficient and a Young's modulus substantially equal to or slightly higher than that of air is provided in the gap. The viscoelastic body cross-sectional area and / or viscoelasticity with respect to the total floor area of the double structure so that the resonance frequency of the double structure does not substantially change depending on the presence or absence of the viscoelastic body. Impact sound insulation type double structure by adjusting the number of body groups . The double structure according to claim 1, wherein a plurality of columnar, frustum-shaped, or beam-shaped viscoelastic bodies are provided in the gap. The double structure of Claim 1 or 2 WHEREIN: The impact sound cutoff type | mold double structure formed by pressing a floor base | substrate and a panel material to the both ends of the said viscoelastic body. 3. The double structure according to claim 1 or 2, wherein one end of the viscoelastic body is fixed to a floor base or a panel material with a thick adhesive, and the floor base is interposed via the viscoelastic body by adjusting the thickness of the adhesive. Double structure that cuts off the impact sound by combining the panel material. The double structure according to any one of claims 1 to 4, wherein the viscoelastic body is made of one or more materials selected from the group consisting of foamed plastic, silicon rubber, glass wool, and rock wool. In any of the double structure of claims 1 to 5, impact loss factor the viscoelastic body is formed by a Young's modulus of ^{2 × 10 5 ~9 × 10 5} (N / m 2) at least 0.4 Sound insulation type double structure.

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